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Fermentation, Volume 9, Issue 11 (November 2023) – 69 articles

Cover Story (view full-size image): Corynebacterium glutamicum is prominent in white biotechnology. Metabolic engineering has enabled the production of the antioxidant astaxanthin. Here, a DoE-guided approach was applied to optimize the basic process parameters, the pH, rDOS, aeration rate, as well as inoculation cell density, in lab-scale stirred bioreactors. The DoE-guided approach revealed a bioprocess design with pH 8, an aeration rate of 0.25 vvm, 30% rDOS, and an initial optical density of 1 in the batch mode. These process conditions were successfully applied to a fed-batch process, resulting in a high cell density, with up to 60 g CDW L−1 biomass and 64 mg L−1 astaxanthin, thus demonstrating an about improvement of 900% compared to that of the batch mode. View this paper
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11 pages, 3678 KiB  
Communication
Candida albicans Adhesion Measured by Optical Nanomotion Detection
Fermentation 2023, 9(11), 991; https://doi.org/10.3390/fermentation9110991 - 20 Nov 2023
Viewed by 1023
Abstract
Cellular adhesion plays an important role in numerous fundamental physiological and pathological processes. Its measurement is relatively complex, requires sophisticated equipment, and, in most cases, cannot be carried out without breaking the links between the studied cell and its target. In this contribution, [...] Read more.
Cellular adhesion plays an important role in numerous fundamental physiological and pathological processes. Its measurement is relatively complex, requires sophisticated equipment, and, in most cases, cannot be carried out without breaking the links between the studied cell and its target. In this contribution, we propose a novel, nanomotion-based, technique that overcomes these drawbacks. The applied force is generated by the studied cell itself (nanomotion), whereas cellular movements are detected by traditional optical microscopy and dedicated software. The measurement is non-destructive, single-cell sensitive, and permits following the evolution of the adhesion as a function of time. We applied the technique on different strains of the fungal pathogen Candida albicans on a fibronectin-coated surface. We demonstrated that this novel approach can significantly simplify, accelerate, and make more affordable living cells–substrate adhesion measurements. Full article
(This article belongs to the Special Issue Yeast Biotechnology 6.0)
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25 pages, 1094 KiB  
Review
An Overview of Lignocellulose and Its Biotechnological Importance in High-Value Product Production
Fermentation 2023, 9(11), 990; https://doi.org/10.3390/fermentation9110990 - 20 Nov 2023
Cited by 1 | Viewed by 1810
Abstract
Lignocellulose consists of cellulose, hemicellulose, and lignin and is a sustainable feedstock for a biorefinery to generate marketable biomaterials like biofuels and platform chemicals. Enormous tons of lignocellulose are obtained from agricultural waste, but a few tons are utilized due to a lack [...] Read more.
Lignocellulose consists of cellulose, hemicellulose, and lignin and is a sustainable feedstock for a biorefinery to generate marketable biomaterials like biofuels and platform chemicals. Enormous tons of lignocellulose are obtained from agricultural waste, but a few tons are utilized due to a lack of awareness of the biotechnological importance of lignocellulose. Underutilizing lignocellulose could also be linked to the incomplete use of cellulose and hemicellulose in biotransformation into new products. Utilizing lignocellulose in producing value-added products alleviates agricultural waste disposal management challenges. It also reduces the emission of toxic substances into the environment, which promotes a sustainable development goal and contributes to circular economy development and economic growth. This review broadly focused on lignocellulose in the production of high-value products. The aspects that were discussed included: (i) sources of lignocellulosic biomass; (ii) conversion of lignocellulosic biomass into value-added products; and (iii) various bio-based products obtained from lignocellulose. Additionally, several challenges in upcycling lignocellulose and alleviation strategies were discussed. This review also suggested prospects using lignocellulose to replace polystyrene packaging with lignin-based packaging products, the production of crafts and interior decorations using lignin, nanolignin in producing environmental biosensors and biomimetic sensors, and processing cellulose and hemicellulose with the addition of nutritional supplements to meet dietary requirements in animal feeding. Full article
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14 pages, 13030 KiB  
Article
Biotechnological Valorization of Cupuaçu By-Products: Solid-State Fermentation for Lipase Production by Yarrowia lipolytica
Fermentation 2023, 9(11), 989; https://doi.org/10.3390/fermentation9110989 - 20 Nov 2023
Viewed by 1078
Abstract
Lipases are enzymes that catalyze the hydrolysis of ester bonds of triacylglycerols at the oil–water interface, generating free fatty acids, glycerol, diacylglycerol, and monoacylglycerol, which can be produced from the fermentation of agro-industrial by-products rich in fatty acids, such as cupuaçu fat cake. [...] Read more.
Lipases are enzymes that catalyze the hydrolysis of ester bonds of triacylglycerols at the oil–water interface, generating free fatty acids, glycerol, diacylglycerol, and monoacylglycerol, which can be produced from the fermentation of agro-industrial by-products rich in fatty acids, such as cupuaçu fat cake. In this study, Yarrowia lipolytica IMUFRJ50682 was used for lipase production from cupuaçu fat cake in solid-state fermentation (SSF) associated with soybean meal. The 2:1 ratio of cupuaçu fat cake/soybean meal increased the lipase activity of Y. lipolytica via SSF by approximately 30.3-fold compared to that in cupuaçu without supplementation. The optimal conditions for Y. lipolytica to produce lipase were obtained by supplementation with peptone, urea, and soybean oil (all at 1.5% w/v), reaching values of up to 70.6 U g−1. These results demonstrate that cupuaçu fat cake associated with soybean meal can be used for lipase production and adds value to cupuaçu by-products. Furthermore, the proper processing of by-products can contribute to improving the economic viability of the biotechnological processing industry and help prevent the accumulation of waste and environmental pollution. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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15 pages, 2314 KiB  
Article
The Bioaugmentation of Electroactive Microorganisms Enhances Anaerobic Digestion
Fermentation 2023, 9(11), 988; https://doi.org/10.3390/fermentation9110988 - 20 Nov 2023
Viewed by 980
Abstract
Direct interspecies electron transfer (DIET) between electroactive microorganisms (EAMs) offers significant potential to enhance methane production, necessitating research for its practical implementation. This study investigated enhanced methane production through DIET in an anaerobic digester bio-augmented with EAMs. A horizontal anaerobic digester (HAD) operated [...] Read more.
Direct interspecies electron transfer (DIET) between electroactive microorganisms (EAMs) offers significant potential to enhance methane production, necessitating research for its practical implementation. This study investigated enhanced methane production through DIET in an anaerobic digester bio-augmented with EAMs. A horizontal anaerobic digester (HAD) operated for 430 days as a testbed to validate the benefits of bioaugmentation with EAMs. Anaerobic digestate slurry, discharged from the HAD, was enriched with EAMs in a bioelectrochemical auxiliary reactor (BEAR) under an electric field. This slurry enriched with EAMs was then recirculated into the HAD. Results showed bio-augmentation with EAMs led to an increase in volatile solids removal from 56.2% to 77.5%, methane production rate from 0.59 to 1.00 L/L.d, methane yield from 0.26 to 0.34 L/g CODr, and biogas methane content from 59.9% to 71.6%. It suggests that bio-augmentation enhances DIET, promoting the conversion of volatile fatty acids to methane and enhancing resilience against kinetic imbalances. The enrichment of EAMs reached optimal efficacy under an electric field intensity of 2.07 V/cm with a mean exposure time of 2.53 days to the electric field in the BEAR. Bio-augmentation with externally enriched EAMs is a feasible and effective strategy to optimize anaerobic digestion processes. Full article
(This article belongs to the Special Issue Advance in Microbial Electrochemical Technologies)
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18 pages, 4629 KiB  
Article
Improving the Quality and Safety of Pu-erh Tea by Inoculation of Saccharomyces cerevisiae and Lactobacillus plantarum
Fermentation 2023, 9(11), 987; https://doi.org/10.3390/fermentation9110987 - 20 Nov 2023
Viewed by 1243
Abstract
The sensory quality and health benefits of Pu-erh tea are mainly determined by microbial fermentation processing. The directed exogenous inoculation of specific microorganisms is an effective method to improve the quality and flavor of Pu-erh tea. In this study, Lactobacillus plantarum and Saccharomyces [...] Read more.
The sensory quality and health benefits of Pu-erh tea are mainly determined by microbial fermentation processing. The directed exogenous inoculation of specific microorganisms is an effective method to improve the quality and flavor of Pu-erh tea. In this study, Lactobacillus plantarum and Saccharomyces cerevisiae were introduced into the fermentation processes of Pu-erh tea, as they are the main contributors to enzyme secretion, to change the tea’s functional components. The raw tea materials, spontaneous fermentation tea and microbiological fermentation tea were analyzed by microbiomics and metabolomics. A total of 248 metabolites were characterized, 71 of which were identified as essential metabolites involved in the metabolic changes. These essential metabolites were produced by specific dominant microbial species with multivariate analysis methods. Metabolites essential to the sensory quality and health benefits of Pu-erh tea, such as flavonoids and free amino acids, were increased in tea samples inoculated with Lactobacillus plantarum and Saccharomyces cerevisiae following fermentation. Fungal diversity decreased after fermentation, and both the diversity and richness of bacteria were significantly decreased. In conclusion, our results demonstrate the advantages of Lactobacillus plantarum and Saccharomyces cerevisiae in forming the unique sensory characteristics of Pu-erh tea, and they indicate that the microbial composition is a key factor in altering the tea’s metabolic profile. Our work establishes a theoretical foundation for the promotion of the safety and quality of Pu-erh tea through exogenous inoculation with Lactobacillus plantarum and Saccharomyces cerevisiae. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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14 pages, 1410 KiB  
Article
Strategies for the Biotransformation of Tung Leaves in Bioethanol Fermentation
Fermentation 2023, 9(11), 986; https://doi.org/10.3390/fermentation9110986 - 19 Nov 2023
Viewed by 892
Abstract
The tung tree (Vernicia fordii Hemsl.), as a woody oilseed crop, has been cultivated in China for thousands of years, and its leaves are rich in cellulose and proteins. The tung leaf is an alternative raw material for the traditional ethanol fermentation [...] Read more.
The tung tree (Vernicia fordii Hemsl.), as a woody oilseed crop, has been cultivated in China for thousands of years, and its leaves are rich in cellulose and proteins. The tung leaf is an alternative raw material for the traditional ethanol fermentation of food crops. In this work, the effects of the simultaneous saccharification fermentation of tung leaves at different substrate concentrations on gas production characteristics, reducing sugars, pH, oxidation–reduction potential (ORP), and ethanol yield were investigated during bioethanol production. In addition, the effect of the initial fermentation pH on the ethanol fermentation of tung leaves was explored. The results showed that during bioethanol production from tung leaves, the pH of the fermentation broth showed a continuous decreasing trend. Moreover, the ORP showed a decreasing trend and then rebounded, and the concentration of reducing sugars initially increased and then decreased. The optimal ethanol yield of 4.99 g/L was obtained when the substrate concentration was 100 g/L. Changes in the initial pH have little effect on yeast activity, but such changes can affect the yeast cell wall structure and substance transport, leading to differences in the ethanol yield. When the initial pH is 7, the maximum ethanol yield is 5.22 g/L. The experimental results indicate that the utilization of tung leaves for bioethanol production has a good potential for development. Full article
(This article belongs to the Section Industrial Fermentation)
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19 pages, 3232 KiB  
Article
Purified Acidic Sophorolipid Biosurfactants in Skincare Applications: An Assessment of Cytotoxic Effects in Comparison with Synthetic Surfactants Using a 3D In Vitro Human Skin Model
Fermentation 2023, 9(11), 985; https://doi.org/10.3390/fermentation9110985 - 18 Nov 2023
Viewed by 1230
Abstract
Acidic sophorolipids (Acidic SL), congeners of sophorolipid biosurfactants, offer a potential alternative to synthetic sodium lauryl ether sulphate (SLES) in skincare applications. However, major challenges associated with the laboratory-based investigations of the cytotoxic effects of Acidic SL have been the utilisation of impure [...] Read more.
Acidic sophorolipids (Acidic SL), congeners of sophorolipid biosurfactants, offer a potential alternative to synthetic sodium lauryl ether sulphate (SLES) in skincare applications. However, major challenges associated with the laboratory-based investigations of the cytotoxic effects of Acidic SL have been the utilisation of impure and/or poorly characterised congeners as well as the use of monolayers of skin cells in in vitro assays. While the former limitation makes glycolipids less attractive for use in academic research and skincare applications, the latter does not provide an accurate representation of the in vivo human skin. The present study, therefore, for the first time, assessed the cytotoxic effects of 96% pure Acidic SL on a 3D in vitro skin model in comparison with SLES, with the aim of investigating a natural alternative to synthetic surfactants for potential use in skincare applications. The 3D in vitro skin model was colonised with Staphylococcus epidermidis for 12 h, and afterwards treated with either Acidic SL or SLES at 100 μg mL−1 for a further 12 h. Subsequently, the cytotoxic effects of Acidic SL in comparison with SLES were assessed using a combination of microbiology, molecular biology techniques, immunoassays, and histological analyses. It was demonstrated that Acidic SL had no deleterious effects on the viability of S. epidermidis, tissue morphology, filaggrin expression, and the production of inflammatory cytokines in comparison to SLES. These findings, in conjunction with the possibility to produce Acidic SL from cheaper renewable natural resources, demonstrate that Acidic SL could offer a potential sustainable alternative to synthetic surfactants. Full article
(This article belongs to the Special Issue Production and Application of Bioactive Biosurfactants)
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15 pages, 2031 KiB  
Article
Metabolic Engineering of Saccharomyces cerevisiae for Conversion of Formate and Acetate into Free Fatty Acids
Fermentation 2023, 9(11), 984; https://doi.org/10.3390/fermentation9110984 - 17 Nov 2023
Viewed by 1122
Abstract
The ever-increasing global energy demand, juxtaposed with critical concerns about greenhouse gas emissions, emphatically underscores the urgency to pivot toward sustainable and eco-friendly energy alternatives. Tapping into microbial metabolism for clean energy generation stands out as a particularly promising avenue in this endeavor. [...] Read more.
The ever-increasing global energy demand, juxtaposed with critical concerns about greenhouse gas emissions, emphatically underscores the urgency to pivot toward sustainable and eco-friendly energy alternatives. Tapping into microbial metabolism for clean energy generation stands out as a particularly promising avenue in this endeavor. Given this backdrop, we delved deeply into the metabolic engineering potential of Saccharomyces cerevisiae, thereby aiming for the bioconversion of formate and acetate—both CO2 derivatives—into free fatty acids (FFAs) as precursors for biofuel production. Our study not only elucidated the metabolic pathways within S. cerevisiae that are tailored for efficient formate and acetate utilization but also shone a light on the meticulous optimization strategies that amplify FFA synthesis. The engineered strains, under refined conditions, exhibited up to an 8-fold increase in an FFA titer, thus reaching a production level of 6.6 g/L, which showcases the potential of microbial metabolism in clean energy generation. Our findings offer a promising step toward harnessing microbial metabolism for sustainable energy production, thereby bridging the gap between waste carbon utilization and greener fuel alternatives. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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13 pages, 8561 KiB  
Article
The Microbial Communities of Anaerobic Respiration and Fermentation Degrading Chitin Exist in the Anaerobic Sludge of Microbial Fuel Cell Anodes
Fermentation 2023, 9(11), 983; https://doi.org/10.3390/fermentation9110983 - 17 Nov 2023
Viewed by 1023
Abstract
Chitin is one of the most abundant polymers in nature, with chitinous biomass often discarded as food waste and marine debris. To explore an effective way to degrade chitin, in this work, anaerobic sludge was inoculated at the anode of a two-chamber microbial [...] Read more.
Chitin is one of the most abundant polymers in nature, with chitinous biomass often discarded as food waste and marine debris. To explore an effective way to degrade chitin, in this work, anaerobic sludge was inoculated at the anode of a two-chamber microbial fuel cell (MFC), and chitin was degraded via anaerobic respiration and fermentation. The results showed that the anaerobic sludge could degrade chitin under both the anaerobic respiration and fermentation modes, with similar degradation rates (7.10 ± 0.96 and 6.96 ± 0.23 C-mg/L·d−1). The open-circuit voltage and output current density could roughly reflect the degradation of chitin in the MFC. The maximum current density generated through the anaerobic sludge degradation of chitin via anaerobic respiration was 160 mA/m2, and the maximum power density was 26.29 mW/m2. The microbial sequencing results revealed substantially different microbial community profiles, with electroactive bacteria (EAB) flora and fermentative bacteria (Longilinea) as the main microbial groups that degraded chitin via anaerobic respiration and fermentation, respectively. Therefore, anaerobic sludge may be a good choice for the treatment of refractory biomass due to its abundant electroactive and fermentative flora. Full article
(This article belongs to the Special Issue Treatment of Municipal Wastewater by Anaerobic Biotechnology)
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19 pages, 1801 KiB  
Article
Influence of Fermentation Time on the Chemical and Functional Composition of Different Cocoa Clones from Southern Colombia
Fermentation 2023, 9(11), 982; https://doi.org/10.3390/fermentation9110982 - 16 Nov 2023
Viewed by 1118
Abstract
Cocoa bean quality depends mainly on genetic material, edaphoclimatic factors and post-harvest processes such as fermentation. The impact of the fermentation process on the chemical and functional composition of different cocoa clones grown in southern Colombia was analyzed. A factorial design with repeated [...] Read more.
Cocoa bean quality depends mainly on genetic material, edaphoclimatic factors and post-harvest processes such as fermentation. The impact of the fermentation process on the chemical and functional composition of different cocoa clones grown in southern Colombia was analyzed. A factorial design with repeated measures over time was used to analyze the effect of clone and fermentation time on chemical characteristics (bromatology, phenolic compounds and antioxidant activity). The bromatological characteristics showed significant differences between clones and fermentation time. Clones EET-8 and CCN-51 showed higher contents of acidity (0.51%), fat (63.61%), protein (12.85%) and carbohydrates (1.63 mg g−1). Moisture, acidity and sucrose increased their values between day 4 and day 6 of fermentation (p < 0.05). Phenolic compounds and antioxidant activity had significant differences between clones, where clones CCN-51 and ICS-95 had high contents of phenols (64.56 mg g−1), flavonoids (3.30 mg g−1) and DPPH reducing capacity (325.55 µmol g−1). In this sense, we consider the FSV-41 clone as the major grain quality index based on the results of chemical composition at the bromatological level, antioxidant activity and phenolic compounds. Full article
(This article belongs to the Section Fermentation for Food and Beverages)
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16 pages, 3693 KiB  
Article
Application of Aromatic Ring Quaternary Ammonium and Phosphonium Salts–Carboxylic Acids-Based Deep Eutectic Solvent for Enhanced Sugarcane Bagasse Pretreatment, Enzymatic Hydrolysis, and Cellulosic Ethanol Production
Fermentation 2023, 9(11), 981; https://doi.org/10.3390/fermentation9110981 - 16 Nov 2023
Viewed by 1013
Abstract
Deep eutectic solvents (DESs) with a hydrophobic aromatic ring structure offer a promising pretreatment method for the selective delignification of lignocellulosic biomass, thereby enhancing enzymatic hydrolysis. Further investigation is needed to determine whether the increased presence of aromatic rings in hydrogen bond receptors [...] Read more.
Deep eutectic solvents (DESs) with a hydrophobic aromatic ring structure offer a promising pretreatment method for the selective delignification of lignocellulosic biomass, thereby enhancing enzymatic hydrolysis. Further investigation is needed to determine whether the increased presence of aromatic rings in hydrogen bond receptors leads to a more pronounced enhancement of lignin removal. In this study, six DES systems were prepared using lactic acid (LA)/acetic acid (AA)/levulinic acid (LEA) as hydrogen bond donors (HBD), along with two independent hydrogen bond acceptors (HBA) (benzyl triethyl ammonium chloride (TEBAC)/benzyl triphenyl phosphonium chloride (BPP)) to evaluate their ability to break down sugarcane bagasse (SCB). The pretreatment of the SCB (raw material) was carried out with the above DESs at 120 °C for 90 min with a solid–liquid ratio of 1:15. The results indicated that an increase in the number of aromatic rings may result in steric hindrance during DES pretreatment, potentially diminishing the efficacy of delignification. Notably, the use of the TEBAC:LA-based DES under mild operating conditions proved highly efficient in lignin removal, achieving 85.33 ± 0.52% for lignin removal and 98.67 ± 2.84% for cellulose recovery, respectively. The maximum digestibilities of glucan (56.85 ± 0.73%) and xylan (66.41 ± 3.06%) were attained after TEBAC:LA pretreatment. Furthermore, the maximum ethanol concentration and productivity attained from TEBAC:LA-based DES-pretreated SCB were 24.50 g/L and 0.68 g/(L·h), respectively. Finally, the comprehensive structural analyses of SCB, employing X-rays, FT-IR, and SEM techniques, provided valuable insights into the deconstruction process facilitated by different combinations of HBDs and HBAs within the DES pretreatment. Full article
(This article belongs to the Special Issue Lignocellulosic Biomass Decomposition and Bioconversion)
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19 pages, 1770 KiB  
Article
Physical Factors Affecting the Scale-Up of Vegetative Insecticidal Protein (Vip3A) Production by Bacillus thuringiensis Bt294
Fermentation 2023, 9(11), 980; https://doi.org/10.3390/fermentation9110980 - 16 Nov 2023
Viewed by 965
Abstract
Vip3A (vegetative insecticidal protein) is a representative member of the Vip3 family, which is widely used for lepidopteran pest control. This Vip3A protein, a non-growth-associated protein, is an effective bioinsecticide against insect pests, but there is relatively little information about its production processes [...] Read more.
Vip3A (vegetative insecticidal protein) is a representative member of the Vip3 family, which is widely used for lepidopteran pest control. This Vip3A protein, a non-growth-associated protein, is an effective bioinsecticide against insect pests, but there is relatively little information about its production processes at large scales. Hence, the effects of environmental factors on Vip3A production by Bacillus thuringiensis Bt294 (antifoam agents, shaking speeds, agitation and aeration rates), as well as controlling physical conditions such as the lowest point of dissolved oxygen and controlling of culture pH, were observed in shaking flasks and bioreactors. The results showed that antifoam agents, flask types and shaking speeds had significant effects on Vip3A and biomass production. Cultivation without pH control and DO control in 5 L bioreactors at lower agitation and aeration rates, which was not favorable for biomass production, resulted in a high Vip3A protein production of 5645.67 mg/L. The scale-up studies of the Vip3A protein production in a pilot-scale 750 L bioreactor gave 3750.0 mg/L. Therefore, this study demonstrated the significant effects of agitation, aeration rates and culture pH on Vip3A production by B. thuringiensis Bt294. Balancing of physical conditions was necessary for obtaining the highest yield of Vip3A by slowing down the production rate of biomass. Moreover, this Vip3A protein has high potential as a bioinsecticide for lepidopteran pest control in organic crops. This information will be important for significantly increasing the Vip3A protein concentration by the bacterium and will be useful for field application at a lower cost. Full article
(This article belongs to the Special Issue Modeling Methods for Fermentation Processes)
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12 pages, 844 KiB  
Article
Characteristics of Koji Using Liquid Starter for Soy Sauce Production
Fermentation 2023, 9(11), 979; https://doi.org/10.3390/fermentation9110979 - 16 Nov 2023
Viewed by 1148
Abstract
Soy sauce is a widely consumed seasoning derived from soybeans and wheat. This study explored the application of innovative techniques to enhance the traditional soy sauce preparation process. Fungi were isolated from a commercial koji starter, and the Aspergillus oryzae strain BJ-1 was [...] Read more.
Soy sauce is a widely consumed seasoning derived from soybeans and wheat. This study explored the application of innovative techniques to enhance the traditional soy sauce preparation process. Fungi were isolated from a commercial koji starter, and the Aspergillus oryzae strain BJ-1 was identified. Additionally, an examination of the methods to optimize the medium composition for liquid starters revealed the impact of varying the medium composition on mycelial growth and enzyme activity. Specifically, compositions containing >10% defatted soybean meal and wheat in a 55:45 ratio resulted in elevated mycelial growth and enzymatic activity, making them promising candidates for koji production. The effect of different inoculation ratios of liquid starter on the characteristics of koji was also investigated, and a 10% inoculum was found to be preferable because of its advantageous characteristics of enzyme activities and pH for soy sauce production. This study contributes to the enhancement of the efficiency and safety of soy sauce production through innovative liquid culture techniques. Full article
(This article belongs to the Section Fermentation for Food and Beverages)
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15 pages, 3585 KiB  
Article
Biochemical Characterization of a Novel Alkaline-Tolerant Xaa-Pro Dipeptidase from Aspergillus phoenicis
Fermentation 2023, 9(11), 978; https://doi.org/10.3390/fermentation9110978 - 15 Nov 2023
Viewed by 782
Abstract
Xaa-Pro dipeptidase (XPD, EC 3.4.13.9; also known as prolidase) catalyzes the hydrolysis of the iminopeptide bond in the trans-Xaa-Pro dipeptides (Xaa represents any amino acid except proline), which makes it find wide applications in food, medical and environmental protection fields. In the present [...] Read more.
Xaa-Pro dipeptidase (XPD, EC 3.4.13.9; also known as prolidase) catalyzes the hydrolysis of the iminopeptide bond in the trans-Xaa-Pro dipeptides (Xaa represents any amino acid except proline), which makes it find wide applications in food, medical and environmental protection fields. In the present study, a novel Xaa-Pro dipeptidase from Aspergillus phoenicis ATCC 14332 (ApXPD) was heterologously expressed and biochemically characterized. Reclassification based on phylogenetic analysis and the version 12.5 MEROPS database showed that this enzyme was the only fungal XPD in the unassigned subfamily that shared the highest sequence identity with Xanthomonas campestris prolidase but not with that from the more related fungal species A. niudulans. As compared with other prolidases, ApXPD also contained a long N-terminal tail (residues 1–63) and an additional region (PAPARLREKL) and used a different arginine residue for dipeptide selectivity. After heterologous expression and partial purification, recombinant ApXPD was highly active and stable over the alkaline range from 8.5 to 10.0, with maximum activity at pH 9.0 and more than 80% activity retained after 1 h incubation at pHs of 8.5–10.0 (55 °C). It also had an apparent optimum temperature of 55 °C and remained stable at 20–30 °C. Moreover, this enzyme was a cobalt-dependent prolidase that only cleaved dipeptides Lys-Pro, Gly-Pro, and Ala-Pro rather than other dipeptides, tripeptides, and tetrapeptides. All these distinct features make A. phoenicis ATCC 14332 XPD unique among currently known prolidases, thus defining a novel Xaa-Pro dipeptidase subfamily. Full article
(This article belongs to the Special Issue Enzymes, Biocatalysis and Biosynthesis)
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14 pages, 1217 KiB  
Article
Modulation of the Aromatic Profile of Verdejo Wine through Sequential Inoculation of Wickerhamomyces anomalus and Saccharomyces cerevisiae
Fermentation 2023, 9(11), 977; https://doi.org/10.3390/fermentation9110977 - 15 Nov 2023
Viewed by 803
Abstract
Two strains of Saccharomyces cerevisiae (Sc01 and Sc02) and one strain of Wickerhamomyces anomalus (Wa) were isolated from organic Verdejo spontaneous fermentations and used for the development of experimental winemaking. Sc01 and Sc02 represented 52.7% of the population of the Saccharomyces strains isolated [...] Read more.
Two strains of Saccharomyces cerevisiae (Sc01 and Sc02) and one strain of Wickerhamomyces anomalus (Wa) were isolated from organic Verdejo spontaneous fermentations and used for the development of experimental winemaking. Sc01 and Sc02 represented 52.7% of the population of the Saccharomyces strains isolated throughout the fermentation process. W. anomalus appeared as the predominant species among the non-Saccharomyces yeasts. Wa turned out to be the strain of this species with the shortest lag phase and positive enzymatic activities, and it was selected for white wine production. Fermentations with unique inoculation of S. cerevisiae strains were compared with sequential inoculation with W. anomalus. The results showed that the sequential inoculations did not affect the fermentation kinetics or physicochemical characteristics of the wines compared with the unique inoculations. However, this study identified a significant impact on the aromatic profiles of the produced wines due to the sequential inoculations. This modification resulted in a similar new aromatic profile in both sequential inoculations, demonstrating common characteristics related to the contribution of W. anomalus. In general, the sequential fermentations were mainly characterized by lower levels of acetate esters and an increase in ethyl acetate levels, whereas lower levels of ethyl octanoate and ethyl dec-9-enoate were detected. Propan-1-ol and butan-1-ol showed an increase in the sequential fermentations, while 4-methylpentan-1-ol and 2-phenylethanol were found in lower concentrations. These results highlight the great influence that the presence of specific strains of native non-Saccharomyces yeasts exerts on the characteristics of elaborate wines. Full article
(This article belongs to the Special Issue Innovative Strategies for the Management of Wine Fermentations)
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13 pages, 1918 KiB  
Article
Characterization of Fermentations with Controlled Temperature with Three Varieties of Coffee (Coffea arabica L.)
Fermentation 2023, 9(11), 976; https://doi.org/10.3390/fermentation9110976 - 15 Nov 2023
Viewed by 1031
Abstract
Temperature control is the starting point for the development of controlled fermentation and improving coffee quality. The characteristics of coffee varieties can influence fermentation behavior. To evaluate the effect of the coffee variety on the behavior of controlled fermentation and on coffee quality, [...] Read more.
Temperature control is the starting point for the development of controlled fermentation and improving coffee quality. The characteristics of coffee varieties can influence fermentation behavior. To evaluate the effect of the coffee variety on the behavior of controlled fermentation and on coffee quality, a completely randomized design was used with three varieties (Castillo, Cenicafé1 and Tabi) and two control temperatures (15 and 30 °C). Spontaneous fermentation was the control for each controlled process. The fermentation time, pH, glucose and lactic acid contents, as well as, the count of mesophiles, yeasts, lactic acid bacteria (LAB) and acetic acid bacteria (AAB), were assessed. The sensory quality of the coffee was classified as very good and excellent based on the variety, with averages above 82 Specialty Coffee Association (SCA) points. The highest values were for the Cenicafé1 variety. Fermentation behaviors were similar among varieties but not based on the given condition. Compared with spontaneous fermentation, the treatment at 15 °C prolonged the degradation of mucilage in more than 24 h; additionally, there were differences in the final pH values, less than 3.5 and close to 4.0, respectively. Quality was not significantly different between the controlled fermentation and the spontaneous fermentation (Wilcoxon test p > 0.05) or between fermentation temperatures (Kruskal–Wallis test p > 0.05). Full article
(This article belongs to the Special Issue Quality and Sensory Analysis of Fermented Products)
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14 pages, 1275 KiB  
Article
Employing Spent Frying Oil as a Feedstock to Produce Short-Chain Organic Acids Using Mixed Microbial Cultures
Fermentation 2023, 9(11), 975; https://doi.org/10.3390/fermentation9110975 - 15 Nov 2023
Viewed by 831
Abstract
Food industry waste and wastewater have been explored in relation to acidogenic fermentation as sources of non-competing food carbohydrates and mixed microbial cultures (MMCs), respectively, with the aim of producing short-chain organic acids (SCOAs) with general applications in polyhydroxyalkanoates (PHAs) production. However, studies [...] Read more.
Food industry waste and wastewater have been explored in relation to acidogenic fermentation as sources of non-competing food carbohydrates and mixed microbial cultures (MMCs), respectively, with the aim of producing short-chain organic acids (SCOAs) with general applications in polyhydroxyalkanoates (PHAs) production. However, studies on acidogenic fermentation using lipidic substrates are scarce. In this work, it was hypothesized that spent frying oil (SFO) could be used as a substrate for SCOA production via MMCs. In this study, oleic acid was used as a model molecule. The characterization of SFO revealed that it is mainly composed of oleic acid (81%), with minor amounts of palmitic, linoleic, and stearic acids. Different MMCs and food-to-microorganism (F/M) ratios were tested. MMCs collected in the aerobic tank of a municipal wastewater treatment plant (AES), at a 1:1 F/M, allowed to obtain the highest SCOA concentration (1.50 g COD/L) and the most diverse profile of SCOAs, with the production of acetic, propionic, butyric, iso-butyric, and valeric acids at 48:17:9:13:13% on a molar basis, respectively. This variety of odd and even SCOAs is of upmost importance, with potential applications in producing PHAs. This work can be considered a starting point for future acidogenic fermentation studies using lipid-based substrates and for the future production of PHAs. Full article
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13 pages, 5285 KiB  
Article
Effect of Vine Age, Dry Farming and Supplemental Irrigation on Color and Phenolic Extraction of cv. Zinfandel Wines from California
Fermentation 2023, 9(11), 974; https://doi.org/10.3390/fermentation9110974 - 15 Nov 2023
Viewed by 869
Abstract
A dry-farmed vineyard block with vines of varying ages including young vines (5 to 12 years old), control vines (2:1 ratio of old to young vines), and old vines (40 to 60 years old) was either submitted to irrigation or dry-farmed. The experimental [...] Read more.
A dry-farmed vineyard block with vines of varying ages including young vines (5 to 12 years old), control vines (2:1 ratio of old to young vines), and old vines (40 to 60 years old) was either submitted to irrigation or dry-farmed. The experimental design yielded six treatments, namely, Irrigated Control, Irrigated Young, Irrigated Old, Dry-farmed Control, Dry-farmed Young, and Dry-farmed Old. Irrigated Young wines were lower in alcohol, anthocyanins, and tannins, as well as higher in pH and hue angle values (H*), than the remaining treatments. Dry-farmed Young wines were higher in anthocyanins and small polymeric pigments, and showed higher color saturation and red hue. However, the magnitude of these differences was small. At pressing, the anthocyanin composition of these Zinfandel wines was largely dominated by malvidin-3-glucoside (60 to 65%), but after 15 months of bottle aging their anthocyanin profile shifted to 60% of anthocyanin derivatives, with small polymeric pigments accounting for more than 70% of the total polymeric pigment content of the wines. Irrigated Old wines and Dry-farmed Old wines did not differ to any significant extent in their basic chemistry, phenolic chemistry (including detailed anthocyanin composition), and chromatic composition. Full article
(This article belongs to the Collection New Aspect on Wine Fermentation)
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16 pages, 2832 KiB  
Article
Effect of Alkaline Mineral Complex Buffer Supplementation on Rumen Fermentation, Rumen Microbiota and Rumen Epithelial Transcriptome of Newborn Calves
Fermentation 2023, 9(11), 973; https://doi.org/10.3390/fermentation9110973 - 14 Nov 2023
Viewed by 938
Abstract
Alkaline mineral complex buffer can improve rumen fermentation and affect the rumen microbiota of dairy cows. Here, we studied the effects of alkaline mineral complex buffer on serum immunity indexes, rumen fermentation and the microbiota of newborn calves. We also investigated changes in [...] Read more.
Alkaline mineral complex buffer can improve rumen fermentation and affect the rumen microbiota of dairy cows. Here, we studied the effects of alkaline mineral complex buffer on serum immunity indexes, rumen fermentation and the microbiota of newborn calves. We also investigated changes in the rumen epithelial transcriptome expression profile. Compared with the control group, at 15 d, the serum contents of TP and GLB in the treatment group increased significantly (p < 0.05). At 30 d, the serum contents of GLB in the treatment group increased significantly (p < 0.05). At 45 d, the serum contents of IgG in the treatment group increased significantly (p < 0.05). At 60 d, the serum contents of TP and IgG in the treatment group increased significantly (p < 0.05). Rumen pH in the treatment groups was significantly increased at different days of age (p < 0.05). The microbial community composition in the rumen was determined using bacterial and archaeal 16S ribosomal RNA (rRNA) gene amplicon-sequencing. Analysis of bacterial composition in the rumen showed that there was no significant difference in bacterial diversity (p > 0.05). At the phylum level, Firmicutes were significantly decreased and Bacteroidetes were significantly increased in the treatment group at 30 d (p < 0.05). At the genus level, Prevotella_1, Olsenella, Christensenellaceae_R-7_group were significantly increased, and Lachnospiraceae_NK3A20_group, Ruminococcaceae_UCG-014 and Ruminococcus_2 were significantly decreased in the treatment group at 30 d (p < 0.05). Christensenellaceae_R-7_group was significantly increased in the treatment group (p < 0.05) at 45 d. Prevotella_9 was significantly decreased, and Prevotellaceae_UCG_001, Christensenellaceae_R-7_group were significantly increased in the treatment group at 60 d (p < 0.05). RNA sequence analysis of the rumen epithelium showed that 232 differentially expressed genes were screened, of which 158 were upregulated and 74 were downregulated. The main enrichment pathway was related to immune regulation. In conclusion, alkaline mineral complex buffer can enhance the body’s immune response, regulate rumen fermentation by regulating the abundance of rumen microbiota and upregulate immune-related genes in rumen tissues to promote immune regulation. The results of this study provide a reference for the early nutritional regulation of newborn calves with an alkaline mineral complex buffer. Full article
(This article belongs to the Section Industrial Fermentation)
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15 pages, 7839 KiB  
Article
Whole-Genome Analysis of Novacetimonas cocois and the Effects of Carbon Sources on Synthesis of Bacterial Cellulose
Fermentation 2023, 9(11), 972; https://doi.org/10.3390/fermentation9110972 - 14 Nov 2023
Viewed by 873
Abstract
Novacetimonas cocois WE7 (formally named Komagataeibacter cocois WE7) is a strain isolated from contaminated coconut milk, capable of producing bacterial cellulose (BC). We sequenced its genome to investigate why WE7 cannot synthesize BC from glucose efficiently. It contains about 3.5 Mb and six [...] Read more.
Novacetimonas cocois WE7 (formally named Komagataeibacter cocois WE7) is a strain isolated from contaminated coconut milk, capable of producing bacterial cellulose (BC). We sequenced its genome to investigate why WE7 cannot synthesize BC from glucose efficiently. It contains about 3.5 Mb and six plasmid DNAs. N. cocois WE7 contains two bcs operons (bacterial cellulose operon, bcs I and bcs II); the absence of bcs III operons may lead to reduced BC production. From genome predictions, glucose, sucrose, fructose, maltose, and glycerol can be utilized to generate BC, with WE7 unable to metabolize carbohydrate carbon sources through the Embden–Meyerhof–Parnas (EMP) pathway, but rather through the Hexose Monophosphate Pathway (HMP) and tricarboxylic acid (TCA) pathways. It has a complete gluconic acid production pathway, suggesting that BC yield might be very low when glucose, maltose, and trehalose are used as carbon sources. This study represents the first genome analysis of N. cocois. This information is crucial for understanding BC production and regulation mechanisms in N. cocois and lays a foundation for constructing engineered strains tailored for diverse BC application purposes. Full article
(This article belongs to the Special Issue New Research on Strains Improvement and Microbial Biosynthesis)
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23 pages, 10973 KiB  
Article
Alleviating Effect of Lactiplantibacillus plantarum NXU0011 Fermented Wolfberry on Ulcerative Colitis in Mice
Fermentation 2023, 9(11), 971; https://doi.org/10.3390/fermentation9110971 - 14 Nov 2023
Viewed by 822
Abstract
As research into the relationship between the gut microbiome and health continues to evolve, probiotics are garnering increasing interest among consumers. Fermentation is recognized as an efficacious biotechnology for augmenting the nutritional and functional attributes of foods. In this study, the ameliorative effects [...] Read more.
As research into the relationship between the gut microbiome and health continues to evolve, probiotics are garnering increasing interest among consumers. Fermentation is recognized as an efficacious biotechnology for augmenting the nutritional and functional attributes of foods. In this study, the ameliorative effects of Lycium barbarum L. lyophilized powder fermented with Lactiplantibacillus plantarum NXU0011 (LP+Ly) on dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) in mice were investigated employing immunohistochemistry, qRT-PCR, macrogenomics, and metabolomics. The results revealed that LP+Ly intervention significantly ameliorated histopathological inflammation in the ulcerated colon, diminished the expression of inflammatory markers such as IL-6, P-STAT3, and miR-214, and enhanced the diversity of intestinal flora in the mouse model group. Moreover, there was an increase in the abundance of beneficial bacteria, including Lactobacillus, Prevotella, and Akkermansia. Metabolomic analysis indicated that 15 metabolites, including citrulline, D-xylose, and α-ketoisovaleric acid, exhibited significant variations following the LP+Ly intervention. The metabolic pathways that displayed substantial differences included tryptophan biosynthesis, arginine biosynthesis, and amino sugar and nucleotide sugar metabolism. LP+Ly effectively improved the inflammatory state within the intestines by modulating arginine biosynthesis, thus alleviating the impact of UC. Full article
(This article belongs to the Special Issue Role of Probiotics in Food Fermentation and Their Health Benefits)
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19 pages, 4478 KiB  
Article
Effect of a Multi-Strain Probiotic on Growth Performance, Lipid Panel, Antioxidant Profile, and Immune Response in Andaman Local Piglets at Weaning
Fermentation 2023, 9(11), 970; https://doi.org/10.3390/fermentation9110970 - 13 Nov 2023
Viewed by 1166
Abstract
This study aimed to investigate the role of a multi-strain probiotic compound containing Bacillus mesentericus, Bacillus coagulans, Enterococcus faecalis, and Clostridium butyricum as an in-feed zinc oxide (ZnO) alternative in growth performance, diarrhea incidence, antioxidant profile, lipid panel, stress, and immunity in [...] Read more.
This study aimed to investigate the role of a multi-strain probiotic compound containing Bacillus mesentericus, Bacillus coagulans, Enterococcus faecalis, and Clostridium butyricum as an in-feed zinc oxide (ZnO) alternative in growth performance, diarrhea incidence, antioxidant profile, lipid panel, stress, and immunity in piglets at weaning. Seventy-two piglets weaned at 27 ± 1 day were divided randomly into three groups with four replicates of six piglets each: (i) a negative control group (WC) fed only a basal diet, (ii) a probiotic group (WB) fed a basal diet with the current probiotic formulation, and (iii) a positive control (PC) group fed a basal diet with 2500 mg/kg ZnO. The experiment was conducted for 28 days. Probiotic supplementation showed a positive effect on growth performance and reduced the diarrhea rate. The mean body weight of the piglets in the WB and PC groups was significantly higher than that of piglets in the WC group (14.88 ± 0.12, 14.97 ± 0.13 vs. 13.80 ± 0.06 kg; p ≤ 0.001). The addition of probiotic to the diet improved the lipid panel; the WB group showed a significantly higher level of high-density lipoprotein cholesterol (mg/dL) (32.67 ± 0.85 in WB vs. 12.48 ± 0.76 in WC; p ≤ 0.001) and lower levels of total cholesterol (mg/dL) (59.78 ± 1.97 in WB vs. 119.11 ± 2.12 in WC; p ≤ 0.001) and low-density lipoprotein cholesterol (mg/dL) (17.90 ± 1.12 in WB vs. 69.10 ± 3.37 in WC; p ≤ 0.001) compared with the negative control group. Moreover, probiotic supplementation enhanced the antioxidant defense system and provided protection from oxidative damage by increasing the concentrations of serum catalase, glutathione-S-transferase, and superoxide dismutase and by decreasing the concentrations of serum malonyldialdehyde and total nitric oxide. Heat shock proteins and other stress markers, such as serum cortisol, were reduced in the probiotic-fed group. The probiotic group also displayed higher levels of serum IgG and IgM at all time points and higher IgA on day 28 compared with the negative control group. Altogether, these results indicate that feeding with the currently used multi-strain probiotic formulation minimizes weaning stress, thereby improving the growth performance, antioxidant profile, lipid panel, and systemic and mucosal immunity. Therefore, multi-strain probiotic compounds may be used to replace ZnO in weaned piglets. Full article
(This article belongs to the Special Issue Probiotics: Mediators in Health and Disease)
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30 pages, 5646 KiB  
Review
Fructooligosaccharides (FOS) Production by Microorganisms with Fructosyltransferase Activity
Fermentation 2023, 9(11), 968; https://doi.org/10.3390/fermentation9110968 - 12 Nov 2023
Viewed by 2153
Abstract
Fructans are fructose-based polymers, defined as fructooligosaccharides (FOS), when they possess a short chain. These molecules are highly appreciated in the food and pharmaceutical international market and have an increasing demand worldwide, mainly for their prebiotic activity and, therefore, for all their health [...] Read more.
Fructans are fructose-based polymers, defined as fructooligosaccharides (FOS), when they possess a short chain. These molecules are highly appreciated in the food and pharmaceutical international market and have an increasing demand worldwide, mainly for their prebiotic activity and, therefore, for all their health benefits to those who consume them constantly. Thus, new natural or alternative FOS production systems of industrial scale are needed. In this regard, microorganisms (prokaryotes and eukaryotes) have the potential to produce them through a wide and diverse number of enzymes with fructosyltransferase activity, which add a fructosyl group to sucrose or FOS molecules to elongate their chain. Microbial fructosyltransferases are preferred in the industry because of their high FOS production yields. Some of these enzymes include levansucrases, inulosucrases, and β-fructofuranosidases obtained and used through biotechnological tools to enhance their fructosyltransferase activity. In addition, characterizing new microorganisms with fructosyltransferase activity and modifying them could help to increase the production of FOS with a specific degree of polymerization and reduce the FOS production time, thus easing FOS obtention. Therefore, the aim of this review is to compile, discuss, and propose new perspectives about the microbial potential for FOS production through enzymes with fructosyltransferase activity and describe the modulation of FOS production yields by exogenous stimuli and endogenous modifications. Full article
(This article belongs to the Special Issue Feature Review Papers in Industrial Fermentation 2023)
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20 pages, 3940 KiB  
Article
Design-of-Experiment-Guided Establishment of a Fermentative Bioprocess for Biomass-Bound Astaxanthin with Corynebacterium glutamicum
Fermentation 2023, 9(11), 969; https://doi.org/10.3390/fermentation9110969 - 11 Nov 2023
Viewed by 1241
Abstract
Corynebacterium glutamicum is prominent in the industrial production of secreted amino acids. Notably, it naturally accumulates the carotenoid pigment decaprenoxanthin in its membranes. Metabolic engineering enabled the production of astaxanthin. Here, a bioprocess for astaxanthin production in lab-scale stirred bioreactors was established by [...] Read more.
Corynebacterium glutamicum is prominent in the industrial production of secreted amino acids. Notably, it naturally accumulates the carotenoid pigment decaprenoxanthin in its membranes. Metabolic engineering enabled the production of astaxanthin. Here, a bioprocess for astaxanthin production in lab-scale stirred bioreactors was established by a DoE-guided approach to optimize the basic process parameters pH, rDOS, aeration rate as well as inoculation cell density. The DoE-guided approach to characterize 2 L scale cultivation revealed that the pH showed the strongest effect on the product formation. Subsequently, an optimum at pH 8, an aeration rate of 0.25 vvm, 30% rDOS and an initial optical density of 1 was established that allowed production of 7.6 ± 0.6 mg L−1 astaxanthin in batch mode. These process conditions were successfully transferred to a fed-batch process resulting in a high cell density cultivation with up to 60 g CDW L−1 biomass and 64 mg L−1 astaxanthin and thus demonstrating an about 9-fold improvement compared to optimal batch conditions. Moreover, pH-shift experiments indicate that the cells can quickly adapt to a change from pH 6 to 8 and start producing astaxanthin, showing the possibility of biphasic bioprocesses for astaxanthin production. Full article
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14 pages, 1191 KiB  
Review
Recent Advancements and Strategies of Improving CO2 Utilization Efficiency in Bio-Succinic Acid Production
Fermentation 2023, 9(11), 967; https://doi.org/10.3390/fermentation9110967 - 10 Nov 2023
Viewed by 1308
Abstract
The production of bio-based succinic acid through microbial CO2 fixation and conversion has gained significant attention as a promising approach to mitigate greenhouse gas emissions. However, the low CO2 utilization efficiency limits the efficient biosynthesis of succinic acid. Therefore, it is [...] Read more.
The production of bio-based succinic acid through microbial CO2 fixation and conversion has gained significant attention as a promising approach to mitigate greenhouse gas emissions. However, the low CO2 utilization efficiency limits the efficient biosynthesis of succinic acid. Therefore, it is crucial from environmental and economic perspectives to enhance the efficiency of CO2 utilization in bio-succinic acid production. This review comprehensively covers the introduction of biosynthetic pathways for microbial CO2 fixation and the conversion of CO2 to succinic acid, as well as the challenges associated with CO2 supply and utilization effectiveness. Moreover, strategies including genetic and metabolic engineering for CO2 fixation, extracellular supply methods of CO2 and some potential technical approaches for CO2 capture (such as micro-nano bubbles, CO2 adsorption material and biofilm) are summarized and presented. Full article
(This article belongs to the Special Issue Feature Review Papers in Fermentation Process Design 2023)
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22 pages, 5342 KiB  
Article
The Characterization of the Inhibitory Substances Produced by Bacillus pumilus LYMC-3 and the Optimization of Fermentation Conditions
Fermentation 2023, 9(11), 966; https://doi.org/10.3390/fermentation9110966 - 10 Nov 2023
Viewed by 844
Abstract
Bacillus pumilus plays a very important role in the biological control of plant diseases. In this study, we conducted indoor biocontrol experiments using the LYMC-3 strain of B. pumilus to assess its efficacy against poplar canker and tea gray blight. Simultaneously, we explored [...] Read more.
Bacillus pumilus plays a very important role in the biological control of plant diseases. In this study, we conducted indoor biocontrol experiments using the LYMC-3 strain of B. pumilus to assess its efficacy against poplar canker and tea gray blight. Simultaneously, we explored the optimal fermentation conditions for the production of inhibitory substances against Phomopsis macrospora and Pestalotiopsis vesicolor. Subsequently, the inhibitory substances were extracted crudely and subjected to a preliminary investigation of their properties. The results of the indoor biocontrol experiments showed that the LYMC-3 strain exhibited disease prevention rates of 44.12% and 48.59% against poplar canker and tea gray blight, respectively. The fermentation optimization experiment showed that a culture medium containing 10 g/L of glucose, 15 g/L of tryptone, and 5 g/L of sodium chloride favored the production of inhibitory substances via the LYMC-3 strain. Among the crude extracts obtained, the non-protein extracts demonstrated the most obvious inhibitory effects. Furthermore, the inhibitory substances exhibited high polarity, excellent thermal stability, and high sensitivity to strong acids and bases. This study establishes a theoretical foundation for the purification and identification of inhibitory substances using the LYMC-3 strain. Additionally, it contributes to elucidating biological control mechanisms and facilitates the application of the LYMC-3 strain in production. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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15 pages, 5153 KiB  
Article
Maximizing Bioethanol Production from Eucalyptus globulus Using Steam Explosion Pretreatment: A Multifactorial Design and Fermenter Development for High Solid Loads
Fermentation 2023, 9(11), 965; https://doi.org/10.3390/fermentation9110965 - 10 Nov 2023
Viewed by 1049
Abstract
Steam explosion pretreatment is suitable for bioethanol production from Eucalyptus globulus wood. Multifactorial experiment designs were used to find the optimal temperature and residence time required to obtain the best glucose yield from the enzymatic hydrolysis of pretreated materials. The chemical composition, crystallinity [...] Read more.
Steam explosion pretreatment is suitable for bioethanol production from Eucalyptus globulus wood. Multifactorial experiment designs were used to find the optimal temperature and residence time required to obtain the best glucose yield from the enzymatic hydrolysis of pretreated materials. The chemical composition, crystallinity index, morphology and polymerization degree of the pretreated materials were correlated with enzymatic accessibility. Simultaneous saccharification and fermentation (SSF) using a fed-batch strategy was applied to three different laboratory-scale fermenters. The optimization of the pretreatment was obtained at 208 °C and 11 min. However, the enzymatic hydrolysis performance did not show significant differences from the material obtained at 196 °C and 9.5 min, which was determined to be the real optimum, owing to its lower energy requirement. The vertical fermenter with type “G” blades and the horizontal fermenter with helical blades were both highly efficient for reaching ethanol yields close to 90% based on dry wood, and ethanol concentrations close to 9.0% v/v. Full article
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21 pages, 3636 KiB  
Review
Lactic Acid Bacteria in Dairy Foods: Prime Sources of Antimicrobial Compounds
Fermentation 2023, 9(11), 964; https://doi.org/10.3390/fermentation9110964 - 10 Nov 2023
Cited by 1 | Viewed by 2059
Abstract
This review presents an in-depth examination of fermented dairy products, highlighting their significance as rich sources of antimicrobial agents. Through a comprehensive study of microbial activities during fermentation, we identify and discuss the rise of bioactive elements with antimicrobial characteristics. Bacteriocins such as [...] Read more.
This review presents an in-depth examination of fermented dairy products, highlighting their significance as rich sources of antimicrobial agents. Through a comprehensive study of microbial activities during fermentation, we identify and discuss the rise of bioactive elements with antimicrobial characteristics. Bacteriocins such as nisin and pediocin play a significant role, as do organic acids such as lactic and acetic acid in providing antimicrobial activity. Challenges, including the enzymes, heat and pH sensitivity of certain compounds, are also touched upon, emphasizing the need for stable delivery for consistent efficacy. Our discussion covers various compounds, including bacteriocins, organic acids, and bioactive peptides, detailing their functions, action mechanisms, and potential applications. Moreover, this review discusses the emerging role of genetic engineering in optimizing lactic acid bacteria strains and exploring the potential of genetically modified organisms in improving the production and efficacy of antimicrobial compounds in dairy products. Additionally, we emphasize the interaction between beneficial microbes and their antimicrobial byproducts and discuss strategies for enhancing the synthesis of these antimicrobial compounds. The review highlights the nutritional significance of fermented dairy items and their potential as a rich source of compounds crucial for improving food safety. Additionally, the review explores challenges and potential solutions related to the stability of these compounds, ensuring their consistent efficacy and contribution to overall well-being. Full article
(This article belongs to the Special Issue Postbiotics from Production to Their Health-Promoting Aspects)
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17 pages, 10207 KiB  
Article
Monitoring β-Fructofuranosidase Activity through Kluyveromyces marxianus in Bioreactor Using a Lab-Made Sequential Analysis System
Fermentation 2023, 9(11), 963; https://doi.org/10.3390/fermentation9110963 - 10 Nov 2023
Viewed by 1544
Abstract
The yeast Kluyveromyces marxianus has shown the potential to produce β-fructofuranosidases, which are enzymes capable of hydrolyzing β-fructofuranosides links of fructans to obtain fructooligosaccharides. The thriving market for fructose syrup and the quality standards imposed by food and pharmaceutical industries have [...] Read more.
The yeast Kluyveromyces marxianus has shown the potential to produce β-fructofuranosidases, which are enzymes capable of hydrolyzing β-fructofuranosides links of fructans to obtain fructooligosaccharides. The thriving market for fructose syrup and the quality standards imposed by food and pharmaceutical industries have generated an increased search for improved, monitored, and controlled production processes. Monitoring β-fructofuranosidase activity in a bioprocess requires the use of adequate sensors and the processing of information using efficient software algorithms; nevertheless, currently, such a sensor does not exist for this purpose. In this contribution, a sequential injection analysis system (SIA) developed in our laboratory was adapted to monitor at-line β-fructofuranosidase activity produced by the yeast K. marxianus. Samples were taken out automatically from the bioreactor and analyzed using 3,5-dinitrosalicylic (DNS). An algorithm was designed to operate the overall components of the lab-made SIA system. The enzymatic activity error obtained with the automatic SIA compared to the off-line laboratory determinations varied from 0.07% at high enzyme concentrations to 20.39% at low β-fructofuranosidase activity. Further development is required to improve the performance of the lab-made SIA system; nevertheless, such a device must be considered as a potential method for monitoring β-fructofuranosidase activity in real time. Full article
(This article belongs to the Special Issue Fermentation Processes: Modeling, Optimization and Control)
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21 pages, 9263 KiB  
Article
Barley Vinegar Relieves Loperamide-Induced Constipation in Mice via the Modulation of the Gut Microbiota and Serum Metabolism
Fermentation 2023, 9(11), 962; https://doi.org/10.3390/fermentation9110962 - 09 Nov 2023
Viewed by 1005
Abstract
This study investigated the effect of barley vinegar on constipation by regulating the structure of intestinal microbiota and the level of short-chain fatty acids (SCFAs). BALB/c mice with loperamide-induced constipation were treated with barley vinegar in the intervention. After treatment, constipation-related factors were [...] Read more.
This study investigated the effect of barley vinegar on constipation by regulating the structure of intestinal microbiota and the level of short-chain fatty acids (SCFAs). BALB/c mice with loperamide-induced constipation were treated with barley vinegar in the intervention. After treatment, constipation-related factors were identified. The effect of barley vinegar on the composition of the intestinal microbiota was evaluated by means of 16S rDNA gene sequencing, and the content of SCFAs in enteral feces was determined via the GC-MS method. Treating constipated mice with barley vinegar accelerated gastrointestinal peristalsis, inhibited the inflammatory response, protected the intestinal barrier, upregulated the production of beneficial intestinal bacteria, and downregulated the production of harmful intestinal bacteria. These therapeutic effects are attributed to reversed gut microbiota dysfunction, which favors the production of intestinal metabolites such as SCFAs. The purgative function of highland barley vinegar may improve the intestinal environment by regulating the balance of intestinal flora and the concentration of SCFAs. In addition, LC-MS metabolomics was used to analyze the effect of barley vinegar on intestinal metabolites in mice with constipation. The results show that the treatment of barley vinegar inhibited the decrease in aspartate, L-threonine, L-serine, L-proline, 3,4-dihydroxymandelic acid, epinephrine, glyceric acid, and 3,4-dihydroxymandelic acid content in intestinal metabolites caused by constipation. 4-2 hydroxy benzene acetic acid and fumaric acid content increased. KEGG pathway analysis showed that digestive system, amino acid and lipid metabolism pathways were important pathways for highland barley vinegar relieving constipation. This study proves that highland barley vinegar mainly regulates lipid metabolism, the digestive system and amino acid metabolism to maintain a steady state, prevent intestinal injury, and improve constipation. In short, this study demonstrates that highland barley vinegar can alleviate constipation in mice and repair colitis damage. Full article
(This article belongs to the Special Issue Fermented Foods for Boosting Health)
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