Fermentation and Bioactive Metabolites 3.0

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Microbial Metabolism, Physiology & Genetics".

Deadline for manuscript submissions: closed (10 May 2022) | Viewed by 48562

Special Issue Editors

Department of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, 64100 Teramo, Italy
Interests: milk; dairy; food analysis; food microbiology and technology; food preservation
Special Issues, Collections and Topics in MDPI journals
Department of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Via R. Balzarini 1, 64100 Teramo, Italy
Interests: microbial ecology; molds; mycotoxin; biofilms; antimicrobial compounds; fermented food
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microorganisms are known to produce secondary metabolites, being exploited as useful bioactive molecules. In addition, they are very diverse both phylogenetically and functionally, being able to carry out complex metabolic transformations. This metabolic versatility leads to a pool of biomolecules that are highly diverse in chemical structure and biological function, and which have potential applications in medicine and the pharmaceutical and food industry fields. In addition, several microorganisms have been exploited to obtain biologically active compounds like peptides, carbohydrates, polyphenols, carotenoids, phytosterols, and fatty acids, which offer health benefits like the prevention of diseases, utilizing different plant- and animal-derived products as substrates. In fact, nowadays, the use of fermented foods is considered a promising alternative to satisfy the growing consumer demands for healthy foods. To increase the production of biomolecules, many strategies, such as the use of specialized single-strain microbial origin cultures, co- cultures exhibiting high diversity allowing complementarity of functions that can modulate their physiology to produce new bioactive molecules, have been used. Accordingly, the design of bioreactor and bioprocesses are also being exploited. This Special Issue aims to publish technological developments (in the form of original research articles, short communications, reviews, mini-reviews, methods articles, perspectives, and opinions, that make a considerable and efficient contribution to the scientific community) used to investigate different aspects of the impact of fermentation on the production of bioactive metabolites. Topics that will be considered include the production of biomolecules in relation to foods, agriculture, industry, biotechnology, and public health.

This is the third version of topic “Fermentation and Bioactive Metabolites”, The success of the first two Editions can be found at:

https://www.mdpi.com/journal/fermentation/special_issues/bioactive_metabolites

https://www.mdpi.com/journal/fermentation/special_issues/bioactive_metabolites_2

Prof. Dr. Annalisa Serio
Prof. Dr. Clemencia Chaves-López
Guest Editors

Manuscript Submission Information

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Keywords

  • Peptides
  • Fatty acids
  • Phenolic compounds
  • Organic volatile compounds
  • Antimicrobial compounds
  • Secondary metabolites.

Published Papers (18 papers)

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19 pages, 2366 KiB  
Article
Exploring the Core Microbiota of Four Different Traditional Fermented Beverages from the Colombian Andes
Fermentation 2022, 8(12), 733; https://doi.org/10.3390/fermentation8120733 - 13 Dec 2022
Cited by 1 | Viewed by 2088
Abstract
Fermentation is an ancient process used to prepare and preserve food. Currently, fermented beverages are part of the culture of people living in the Colombian Andean Region, and they are a vital part of their cosmology and ancestral vision. Chicha, Forcha, Champús, and [...] Read more.
Fermentation is an ancient process used to prepare and preserve food. Currently, fermented beverages are part of the culture of people living in the Colombian Andean Region, and they are a vital part of their cosmology and ancestral vision. Chicha, Forcha, Champús, and Masato are some of the most common Colombian Andes region’s traditional fermented beverages. These drinks come from the fermentation of maize (Zea maize), but other cereals such as wheat or rye, could be used. The fermentation is carried out by a set of bacteria and yeasts that provide characteristic organoleptic properties of each beverage. In this work, the information collected from the metagenomics analyses by sequencing ITS 1-4 (Internal Transcriber Spacer) and the 16S ribosomal gene for fungi and the V3-V4 region of the rDNA for bacteria allowed us to identify the diversity present in these autochthonous fermented beverages made with maize. The sequencing analysis showed the presence of 39 bacterial and 20 fungal genera. In addition, we determined that only nine genera of bacteria and two genera of fungi affect the organoleptic properties of smell, colour, and flavour, given the production of compounds such as lactic acid, alcohol, and phenols, highlighting the critical role of these microorganisms. Our findings provide new insights into the core microbiota of these beverages, represented by Lactobacillus fermentum, Acetobacter pasteurianus, and Saccharomyces cerevisiae. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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13 pages, 2036 KiB  
Article
Improving Ergometrine Production by easO and easP Knockout in Claviceps paspali
Fermentation 2022, 8(6), 263; https://doi.org/10.3390/fermentation8060263 - 02 Jun 2022
Cited by 4 | Viewed by 1893
Abstract
Ergometrine is widely used for the treatment of excessive postpartum uterine bleeding. Claviceps paspali is a common species for industrial production of ergometrine, which is often accompanied by lysergic acid α-hydroxyethylamide (LAH) and lysergic acid amide (LAA). Currently, direct evidence on the [...] Read more.
Ergometrine is widely used for the treatment of excessive postpartum uterine bleeding. Claviceps paspali is a common species for industrial production of ergometrine, which is often accompanied by lysergic acid α-hydroxyethylamide (LAH) and lysergic acid amide (LAA). Currently, direct evidence on the biosynthetic mechanism of LAH and LAA from lysergic acid in C. paspali is absent, except that LAH and LAA share the common precursor with ergometrine and LAA is spontaneously transformed from LAH. A comparison of the gene clusters between C. purpurea and C. paspali showed that the latter harbored the additional easO and easP genes. Thus, the knockout of easO and easP in the species should not only improve the ergometrine production but also elucidate the function. In this study, gene knockout of C. paspali by homologous recombination yielded two mutants ∆easOhetero-1 and ∆easPhetero-34 with ergometrine titers of 1559.36 mg∙L−1 and 837.57 mg∙L−1, which were four and two times higher than that of the wild-type control, respectively. While the total titer of LAH and LAA of ∆easOhetero-1 was lower than that of the wild-type control. The Aspergillus nidulans expression system was adopted to verify the function of easO and easP. Heterologous expression in A. nidulans further demonstrated that easO, but not easP, determines the formation of LAA. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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14 pages, 1179 KiB  
Article
Thermosonication of Broccoli Florets Prior to Fermentation Increases Bioactive Components in Fermented Broccoli Puree
Fermentation 2022, 8(5), 236; https://doi.org/10.3390/fermentation8050236 - 19 May 2022
Cited by 4 | Viewed by 1623
Abstract
The aim of this study was to compare the effects of thermosonication (18 kHz at 60 °C for 7 min) pre-treatment with thermal treatment alone (60 °C for 7 min) of broccoli florets prior to pureeing and fermentation on selected bioactive components of [...] Read more.
The aim of this study was to compare the effects of thermosonication (18 kHz at 60 °C for 7 min) pre-treatment with thermal treatment alone (60 °C for 7 min) of broccoli florets prior to pureeing and fermentation on selected bioactive components of fermented broccoli puree. Both thermal and thermosoncation pre-treatments significantly increased the rate of acidification of broccoli puree compared to control untreated broccoli puree, with the time to reach pH 4 being 8.25, 9.9, and 24 h, respectively, for thermally treated, thermosonicated, and control samples. The highest sulforaphane yield of 7268 µmol/kg dry weight (DW) was observed in the thermosonicated samples, followed by 6227 µmol/kg DW and 3180 µmol/kg DW in the thermally treated and untreated samples, respectively. The measurable residual glucoraphanin content was 1642 µmol/kg DW, 1187 µmol/kg DW, and 1047 µmol/kg DW, respectively, in the thermonsonicated, thermally pre-treated, and control fermented samples, indicating that pre-treatment specially by thermosonication increases the extractability of glucoraphanin. The higher sulforaphane yield in the thermosonicated and thermally pre-treated samples could be due to increased extractability and accessibility of glucoraphanin and interaction with myrosinase in addition to the inactivation of epthiospecifier protein (ESP), which directs conversion away from sulforaphane into sulforaphane nitrile. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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12 pages, 1390 KiB  
Article
Monascus purpureus Fermented Product Ameliorates Learning and Memory Impairment in the Amyloid Precursor Protein Transgenic J20 Mouse Model of Alzheimer’s Disease
Fermentation 2022, 8(5), 193; https://doi.org/10.3390/fermentation8050193 - 24 Apr 2022
Viewed by 1827
Abstract
Evidence suggests that various hallmarks such as amyloid overproduction, tau dysfunction, insulin resistance/diabetic mechanisms, and neuroinflammation are associated with Alzheimer’s disease (AD). This study investigated the bioactive functions of ankaflavin (AK) and monascin (MS) in the fermented product of Monascus purpureus and found [...] Read more.
Evidence suggests that various hallmarks such as amyloid overproduction, tau dysfunction, insulin resistance/diabetic mechanisms, and neuroinflammation are associated with Alzheimer’s disease (AD). This study investigated the bioactive functions of ankaflavin (AK) and monascin (MS) in the fermented product of Monascus purpureus and found their abilities to ameliorate AD by modifying several important pathogenic factors including improved cognitive function, reversed behavioral deficits, reduced hippocampal β-amyloid peptide (Aβ) burden, decreased tau hyper-phosphorylation, and reduced neuroinflammation in the J20 mouse model of AD compared to wild type. Monascus purpureus fermented product (MPFP) was suggested to act as a peroxisome proliferator-activated receptor (PPAR)-γ agonist and it was compared against the action of a well-known anti-diabetic PPAR-γ agonist rosiglitazone. MPFP could be a promising therapeutic strategy for disease modification in AD. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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18 pages, 4734 KiB  
Article
Kinetic Study of Fungal Growth of Several Tanninolytic Strains Using Coffee Pulp Procyanidins
Fermentation 2022, 8(1), 17; https://doi.org/10.3390/fermentation8010017 - 31 Dec 2021
Cited by 3 | Viewed by 2560
Abstract
Procyanidins are bioactive molecules with industrial and pharmaceutical relevance, they are present in recalcitrant agro-industrial wastes that are difficult to degrade. In this study, we evaluated the potential consumption of procyanidins from Aspergillus niger and Trichoderma harzianum strains in submerged fermentations. For this [...] Read more.
Procyanidins are bioactive molecules with industrial and pharmaceutical relevance, they are present in recalcitrant agro-industrial wastes that are difficult to degrade. In this study, we evaluated the potential consumption of procyanidins from Aspergillus niger and Trichoderma harzianum strains in submerged fermentations. For this purpose, a culture medium containing salts, glucose, and procyanidins was formulated, where procyanidins were added to the medium after the near-total consumption of glucose. The submerged cultures were carried out in amber flasks at 30 °C and 120 rpm. The addition of procyanidins to the culture medium increased the formation of micellar biomass for all the strains used. The use of glucose affected the growth of A. niger GH1 and A. niger HS1, however, in these assays, a total consumption of procyanidins was obtained. These results show that the consumption of procyanidins by fungal strains in submerged fermentations was influenced by the pH, the use of glucose as the first source of carbon, and the delayed addition of procyanidins to the medium. The study showed that A. niger and T. harzianum strains can be used as a natural strategy for the consumption or removal of procyanidins present in recalcitrant residues of risk to the environment and human health. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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13 pages, 2739 KiB  
Article
Influence of Salinity on the Microbial Community Composition and Metabolite Profile in Kimchi
Fermentation 2021, 7(4), 308; https://doi.org/10.3390/fermentation7040308 - 13 Dec 2021
Cited by 27 | Viewed by 5678
Abstract
Kimchi, a popular traditional Korean fermented food, is produced by fermenting vegetables with various spices and salt. Salt plays an important role in the preparation of kimchi and affects its taste and flavor. This study aimed to investigate the effects of salinity on [...] Read more.
Kimchi, a popular traditional Korean fermented food, is produced by fermenting vegetables with various spices and salt. Salt plays an important role in the preparation of kimchi and affects its taste and flavor. This study aimed to investigate the effects of salinity on kimchi fermentation. The salinities of five sets of kimchi samples were adjusted to 1.4%, 1.7%, 2.0%, 2.2%, and 2.5%. The characteristics of each kimchi sample, including its pH, acidity, free sugar content, free amino acid content, organic acid content, and microbial community composition, were evaluated during kimchi fermentation. The low-salinity kimchi sample showed a rapid decline in the pH at the beginning of the fermentation process, a relatively high abundance of Leuconostoc mesenteroides, and high mannitol production. In the late fermentation period, Latilactobacillus sakei had a higher abundance in the kimchi sample with high salinity than in other samples. In the initial stage of fermentation, the metabolite composition did not differ based on salinity, whereas the composition was considerably altered from the third week of fermentation. The findings showed variations in the characteristics and standardized manufacturing processes of kimchi at various salt concentrations. Therefore, salinity significantly affected the types and concentrations of fermentation metabolites in kimchi. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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19 pages, 1690 KiB  
Article
Extractive Fermentation for Recovery of Bacteriocin-Like Inhibitory Substances Derived from Lactococcus lactis Gh1 Using PEG2000/Dextran T500 Aqueous Two-Phase System
Fermentation 2021, 7(4), 257; https://doi.org/10.3390/fermentation7040257 - 02 Nov 2021
Cited by 7 | Viewed by 2401
Abstract
This work aimed to optimize the parameters affecting partitioning of a bacteriocin-like inhibitory substances (BLIS) from Lactococcus lactis Gh1 in extractive fermentation using polyethylene glycol (PEG)/dextran aqueous two-phase system (ATPS). This system was developed for the simultaneous cell cultivation and downstream processing of [...] Read more.
This work aimed to optimize the parameters affecting partitioning of a bacteriocin-like inhibitory substances (BLIS) from Lactococcus lactis Gh1 in extractive fermentation using polyethylene glycol (PEG)/dextran aqueous two-phase system (ATPS). This system was developed for the simultaneous cell cultivation and downstream processing of BLIS. Results showed that the molecular weight of PEG, PEG concentration, and dextran T500 affect the partition coefficient (K), purification factor (PF), and yield of BLIS partitioning. ATPS composed of 10% (w/w) PEG2000 and 8% (w/w) dextran T500, provided the greatest conditions for the extractive BLIS production. The K (1.00 ± 0.16), PF (2.92 ± 0.37) and yield (77.24 ± 2.81%) were increased at selected orbital speed (200 rpm) and pH (pH 7). Sustainable growth of the cells in the bioreactor and repeated fermentation up to the eighth extractive batch were observed during the scale up process, ensuring a continuous production and purification of BLIS. Hence, the simplicity and effectiveness of ATPS in the purification of BLIS were proven in this study. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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12 pages, 2202 KiB  
Article
Effect of Ellagic Acid on Fermentation Quality and Bacterial Community of Stylo Silage
Fermentation 2021, 7(4), 256; https://doi.org/10.3390/fermentation7040256 - 02 Nov 2021
Cited by 9 | Viewed by 1759
Abstract
This study was conducted to investigate the effect of ellagic acid on the bacterial community and fermentability of stylo silage. Three treatments of stylo silage were used: control (CK) and treated with 1% or 2% ellagic acid (EA1 and EA2) on a fresh [...] Read more.
This study was conducted to investigate the effect of ellagic acid on the bacterial community and fermentability of stylo silage. Three treatments of stylo silage were used: control (CK) and treated with 1% or 2% ellagic acid (EA1 and EA2) on a fresh matter basis. All silage was stored at ambient temperature and opened on days 3, 7, 14, and 30. Fermentation characteristics, protein fraction, and bacteria community of all periods of silage were analyzed. Results showed that dry matter and crude protein content were increased, and pH value, number of coliform bacteria, contents of acetic acid, and ammonium nitrogen were decreased with the addition of ellagic acid. The antioxidant activity of 1% and 2% ellagic acid treated silages was significantly higher than the control. Meanwhile, the relative abundance of Klebsiella and Clostridium was decreased with the addition of ellagic acid, and the abundance of Lactobacillus, Weissella, and Enterococcus was increased with prolonged days of ensiling. Adding ellagic acid to stylo silage could improve the fermentation quality and preservation of protein, and reduce the abundance of harmful bacteria. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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10 pages, 11752 KiB  
Article
Solid State Fermentation of Shrimp Shell Waste Using Pseudonocardia carboxydivorans 18A13O1 to Produce Bioactive Metabolites
Fermentation 2021, 7(4), 247; https://doi.org/10.3390/fermentation7040247 - 29 Oct 2021
Cited by 6 | Viewed by 2906
Abstract
Marine actinomycetes are prolific microorganisms; however, knowledge of their diversity, distribution, and secondary metabolites is limited. Marine actinomycetes represent an untapped source of novel bioactive compounds. In this study, we investigated shrimp shell as substrates for model production bioactive metabolites from actinomycetes under [...] Read more.
Marine actinomycetes are prolific microorganisms; however, knowledge of their diversity, distribution, and secondary metabolites is limited. Marine actinomycetes represent an untapped source of novel bioactive compounds. In this study, we investigated shrimp shell as substrates for model production bioactive metabolites from actinomycetes under solid state fermentation (SSF) conditions. A total of fifteen actinomycetes were isolated from six sponges and one tunicate. The isolated actinomycetes were grown on solid shrimp shells. Cultures of actinomycetes were extracted with ethyl acetate (EtOAc) and extracts were bioassayed for activity against Staphylococcus aureus. One isolate 18A13O1 from the sponge, Rhabdastrella globostellata, exhibited antibacterial activity on primary screening compared to the other samples and was chosen for further study. Visualization using SEM showed aerial and substrate mycelia. Through phylogenetic analysis, it was confirmed that isolate 18A13O1 is a Pseudonocardia carboxydivorans. Purification of an EtOAc extract yielded A13B2, which showed a minimum inhibition concentration against S. aureus at 15.6 μg/mL. It can be concluded that this basic information is very important for further studies related to the development of the production of bioactive secondary metabolites through the solid state fermentation process. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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10 pages, 1327 KiB  
Article
Production of New Isoflavone Diglucosides from Glycosylation of 8-Hydroxydaidzein by Deinococcus geothermalis Amylosucrase
Fermentation 2021, 7(4), 232; https://doi.org/10.3390/fermentation7040232 - 16 Oct 2021
Cited by 6 | Viewed by 1819
Abstract
8-Hydroxydaidzein (8-OHDe) is a non-natural isoflavone polyphenol isolated from fermented soybean foods. 8-OHDe exhibits a wide range of pharmaceutical activities. However, both the poor solubility and instability of 8-OHDe limit its applications. To resolve the limitations of 8-OHDe, Deinococcus geothermalis amylosucrase (DgAS) has [...] Read more.
8-Hydroxydaidzein (8-OHDe) is a non-natural isoflavone polyphenol isolated from fermented soybean foods. 8-OHDe exhibits a wide range of pharmaceutical activities. However, both the poor solubility and instability of 8-OHDe limit its applications. To resolve the limitations of 8-OHDe, Deinococcus geothermalis amylosucrase (DgAS) has previously been used to glycosylate 8-OHDe to produce soluble and stable 8-OHDe-7-O-α-glucopyranoside (8-OHDe-7-G) in a 0.5 h reaction time. In this study, we aimed to use DgAS and an extended reaction time to produce 8-OHDe diglucosides. At least three 8-OHDe derivatives were produced after a 24 h reaction time, and two major products were successfully purified and identified as new compounds: 8-OHDe-7-O-[α-glucopyranosyl-(1→6)-α-glucopyranoside] (8-OHDe-7-G2) and 8-OHDe-7,4′-O-α-diglucopyranoside (8-OHDe-7-G-4′-G). 8-OHDe-7-G-4′-G showed a 4619-fold greater aqueous solubility than 8-OHDe. In addition, over 92% of the 8-OHDe diglucosides were stable after 96 h, while only 10% of the 8-OHDe could be detected after being subjected to the same conditions. The two stable 8-OHDe diglucoside derivatives have the potential for pharmacological usage in the future. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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11 pages, 1808 KiB  
Article
Silver Ion-Complexation High-Speed Countercurrent Chromatography Coupled with Prep-HPLC for Separation of Sesquiterpenoids from Germacrene A Fermentation Broth
Fermentation 2021, 7(4), 230; https://doi.org/10.3390/fermentation7040230 - 14 Oct 2021
Viewed by 1669
Abstract
A silver ion high-speed counter-current chromatography ([Ag+]-HSCCC) was developed to separate and purify five sesquiterpenoids from germacrene A fermentation broth. The solvent system was consisted of n-hexane-methanol-silver nitrate (3 mol/L) solution (10:9.5:0.5, v/v). By employing this chromatographic [...] Read more.
A silver ion high-speed counter-current chromatography ([Ag+]-HSCCC) was developed to separate and purify five sesquiterpenoids from germacrene A fermentation broth. The solvent system was consisted of n-hexane-methanol-silver nitrate (3 mol/L) solution (10:9.5:0.5, v/v). By employing this chromatographic protocol, five sesquiterpenoids named β-elemene (1; 54.1 mg), germacrene A (2; 28.5 mg), γ-selinene (3; 4.6 mg), β-selinene (4; 3.4 mg), and α-selinene (5; 1.3 mg) were obtained successfully from 500 mg extracted crude sample with purities of 97.1%, 95.2%, 98.2%, 96.3% and 98.5%, respectively, combined with preparative HPLC. The results reveal that the addition of metal ion in biphasic solvent system significantly improved the HSCCC separation factor of sesquiterpenoids. Meanwhile, our study also provided an alternate approach to separate the compounds with less polarity, also geometrical isomers and various natural product classes. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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10 pages, 967 KiB  
Communication
Applying a ‘Metabolic Funnel’ for Phenol Production in Escherichia coli
Fermentation 2021, 7(4), 216; https://doi.org/10.3390/fermentation7040216 - 05 Oct 2021
Viewed by 1979
Abstract
Phenol is an important petrochemical that is conventionally used as a precursor for synthesizing an array of plastics and fine chemicals. As an emerging alternative to its traditional petrochemical production, multiple enzyme pathways have been engineered to date to enable its renewable biosynthesis [...] Read more.
Phenol is an important petrochemical that is conventionally used as a precursor for synthesizing an array of plastics and fine chemicals. As an emerging alternative to its traditional petrochemical production, multiple enzyme pathways have been engineered to date to enable its renewable biosynthesis from biomass feedstocks, each incorporating unique enzyme chemistries and intermediate molecules. Leveraging all three of the unique phenol biosynthesis pathways reported to date, a series of synthetic ‘metabolic funnels’ was engineered, each with the goal of maximizing net precursor assimilation and flux towards phenol via the parallel co-expression of multiple distinct pathways within the same Escherichia coli host. By constructing and evaluating all possible binary and tertiary pathway combinations, one ‘funnel’ was ultimately identified, which supported enhanced phenol production relative to all three individual pathways by 16 to 69%. Further host engineering to increase endogenous precursor availability then allowed for 26% greater phenol production, reaching a final titer of 554 ± 19 mg/L and 28.8 ± 0.34 mg/g yield on glucose. Lastly, using a diphasic culture including dibutyl phthalate for in situ phenol extraction, final titers were further increased to a maximum of 812 ± 145 mg/L at a yield of 40.6 ± 7.2 mg/g. The demonstrated ‘funneling’ pathway holds similar promise in support of phenol production by other, non-E. coli hosts, while this general approach can be readily extended towards a diversity of other value-added bioproducts of interest. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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15 pages, 2482 KiB  
Article
Citric Acid Influences the Dynamics of the Fermentation Quality, Protease Activity and Microbial Community of Mulberry Leaf Silage
Fermentation 2021, 7(3), 185; https://doi.org/10.3390/fermentation7030185 - 09 Sep 2021
Cited by 5 | Viewed by 2493
Abstract
Mulberry (Morus alba) leaves has performed well as a high-quality protein supplement for livestock and enriches the edible resources of livestock. However, the harvest of mulberry leaves is seasonal and occurs mainly during the rainy season in southeast China; therefore, humid [...] Read more.
Mulberry (Morus alba) leaves has performed well as a high-quality protein supplement for livestock and enriches the edible resources of livestock. However, the harvest of mulberry leaves is seasonal and occurs mainly during the rainy season in southeast China; therefore, humid and sultry weather causes serious losses of mulberry leaf biomass, which pose a challenge for the preservation of mulberry leaves. In this study, we used the silage fermentation method to preserve mulberry leaves and investigated the effects of citric acid on the silage quality of mulberry leaves. Mulberry leaves were ensiled with or without 1% citric acid and 2% citric acid. The chemical composition, protein fraction and microbial community of mulberry leaf silages were analyzed. The results showed that the silage treated with citric acid had a higher dry matter recovery and lactic acid content and a lower acetic acid content, non-protein nitrogen content and ammonia-N content; citric acid also inhibited the activities of carboxypeptidase and aminopeptidase. Moreover, citric acid increased Lactobacillus abundance in silages and decreased the abundance of undesired microorganisms, such as Enterobacter. In summary, the addition of citric acid improved the fermentation quality of mulberry leaf silages, with 2% citric acid being more effective than 1% citric acid. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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14 pages, 4759 KiB  
Article
Immunomodulatory Effect of Sasa quelpaertensis Leaves Fermentation Products in Mice
Fermentation 2021, 7(3), 142; https://doi.org/10.3390/fermentation7030142 - 03 Aug 2021
Viewed by 1735
Abstract
The purpose of this study was to enhance the immune-enhancing activity of mushroom strains through fermentation to promote food use of leaf extracts of S. quelpaertensis containing β-glucan. We evaluated the immunomodulatory effect of extracts from fermented S. quelpaertensis leaves (SQGL, SQHE, SQPL). [...] Read more.
The purpose of this study was to enhance the immune-enhancing activity of mushroom strains through fermentation to promote food use of leaf extracts of S. quelpaertensis containing β-glucan. We evaluated the immunomodulatory effect of extracts from fermented S. quelpaertensis leaves (SQGL, SQHE, SQPL). S. quelpaertensis leaves fermentation products were prepared by using mushroom mycelia (Ganoderma lucidum, Hericium erinaceum, Phellinus linteus). The content of β-glucan, a major substance in S. quelpaertensis leaves fermentation products, was 3.73 ± 0.50 mg/mL in the extract (SQ) of S. quelpaertensis leaves. The fermented mushrooms, SQGL, were the highest at 5.57 ± 0.86 mg/100 mL, followed by SQHE and SQPL, and the β-glucan content of all of the glucan was >75.3%. To test the immune activity, S. quelpaertensis leaf fermentation products were administered to mice at different doses (60, 160, and 360 mg/kg) for two weeks. Th cell and macrophage populations were found to increase significantly at all three doses compared to the negative control after two weeks. SQGL and SQHE were highest at 160 mg/kg, and SQPL showed the highest Th cell proliferation at 60 mg/kg. In addition, the production of IFN-γ, IL-4, IL-10, and nitric oxide was significantly higher than that of the negative control after two weeks. In particular, an increase was seen at a low concentration of 60 mg/kg. Therefore, the S. quelpaertensis leaf fermentation product can be very useful as a functional ingredient for enhancing immunity. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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14 pages, 1565 KiB  
Article
Ability of Yeast Metabolic Activity to Reduce Sugars and Stabilize Betalains in Red Beet Juice
Fermentation 2021, 7(3), 105; https://doi.org/10.3390/fermentation7030105 - 05 Jul 2021
Cited by 5 | Viewed by 3040
Abstract
To lower the risk of obesity, diabetes, and other related diseases, the WHO recommends that consumers reduce their consumption of sugars. Here, we propose a microbiological method to reduce the sugar content in red beet juice, while incurring only slight losses in the [...] Read more.
To lower the risk of obesity, diabetes, and other related diseases, the WHO recommends that consumers reduce their consumption of sugars. Here, we propose a microbiological method to reduce the sugar content in red beet juice, while incurring only slight losses in the betalain content and maintaining the correct proportion of the other beet juice components. Several yeast strains with different metabolic activities were investigated for their ability to reduce the sugar content in red beet juice, which resulted in a decrease in the extract level corresponding to sugar content from 49.7% to 58.2%. This strategy was found to have the additional advantage of increasing the chemical and microbial stability of the red beet juice. Only slight losses of betalain pigments were noted, to final concentrations of 5.11% w/v and 2.56% w/v for the red and yellow fractions, respectively. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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18 pages, 2879 KiB  
Article
Increased Extracellular Saponin Production after the Addition of Rutin in Truffle Liquid Fermentation and Its Antioxidant Activities
Fermentation 2021, 7(3), 103; https://doi.org/10.3390/fermentation7030103 - 29 Jun 2021
Cited by 1 | Viewed by 2378
Abstract
Saponins possess a variety of pharmacological effects and exhibit great potential in the food industry as bioactive substances. In this study, extracellular saponin production via the liquid fermentation of Tuber melanosporum occurred with the addition of rutin. For this purpose, medium composition and [...] Read more.
Saponins possess a variety of pharmacological effects and exhibit great potential in the food industry as bioactive substances. In this study, extracellular saponin production via the liquid fermentation of Tuber melanosporum occurred with the addition of rutin. For this purpose, medium composition and culture conditions were optimized using single-factor experiments and an orthogonal experiment design. The optimal medium consisted of glucose (43.5 g/L), peptone (6 g/L), KH2PO4 (1.15 g/L), NaCl (0.2 g/L), vitamin B2 (0.082 g/L), vitamin B6 (0.1 g/L), vitamin C (0.02 g/L), and rutin (4.8 g/L). The culture conditions were as follows: 12.5% (v/v) inoculation, medium volume of 50 mL/250 mL flask, culture temperature of 24 °C, shaker speed of 190 rpm, initial pH of 5.7, and culture time of 96 h. Finally, a maximal extracellular saponin content of 0.413 g/L was obtained, which was 134.7% higher than that in the base medium. Rutin proved to be an excellent promoter, because the saponin production was increased by 50.2% compared to that in the optimized medium without rutin. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, hydroxyl radical scavenging activity, and ferric reducing antioxidant power of truffle saponins reached 94.13%, 79.26%, and 42.22 mM, respectively. This study provides a useful strategy for fungal bioactive saponin production by liquid fermentation with the addition of flavonoid compounds. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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12 pages, 1887 KiB  
Article
Microbial Composition of Fermented Korean Soy Paste (Doenjang) Prepared by Adding Different Herbs during Fermentation
Fermentation 2021, 7(2), 93; https://doi.org/10.3390/fermentation7020093 - 10 Jun 2021
Cited by 3 | Viewed by 2789
Abstract
The microbiota involved in Korean soy paste (doenjang) fermentation are the key factors determining its quality aspects. In this study, doenjang was prepared by adding three different herbs (Peppermint, Korean mint, and Coriander), and their effect on the microbiota composition was evaluated by [...] Read more.
The microbiota involved in Korean soy paste (doenjang) fermentation are the key factors determining its quality aspects. In this study, doenjang was prepared by adding three different herbs (Peppermint, Korean mint, and Coriander), and their effect on the microbiota composition was evaluated by 16S rRNA metagenomic analyses. The β-diversity statistics indicated clear distinctions in the doenjang microbiota after the addition of herbs. A microbial composition analysis revealed that Tetragenococcus was among the dominant genera in the four doenjang groups, with a relatively higher abundance in the Korean mint group. In the Peppermint and Korean mint doenjang groups, the levels of undesirable microbes, such as opportunistic pathogens belonging to the genera Sphingobacterium and Pantoea, were significantly reduced. Additionally, other desirable microbes that are known to exhibit beneficial properties and produce bioactive compounds, such as Saccharopolyspora and Buttiauxella, were present at significantly higher levels. Significant negative correlations between members of the Bacillaceae and Halomonadaceae, Lactobacillaceae and Tissierellaceae, and the Lacobacillaceae and Erwiniaceae families were observed, indicating possible antagonistic relationships. Taken together, our results demonstrated that the incorporation of herbs, particularly Peppermint and Korean mint, during doenjang fermentation resulted in significant shifts in the microbial composition and could be utilized for beneficial effect on its fermentation. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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Review

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11 pages, 876 KiB  
Review
Obtaining Antioxidants and Natural Preservatives from Food By-Products through Fermentation: A Review
Fermentation 2021, 7(3), 106; https://doi.org/10.3390/fermentation7030106 - 07 Jul 2021
Cited by 17 | Viewed by 6194
Abstract
Industrial food waste has potential for generating income from high-added-value compounds through fermentation. Solid-state fermentation is promising to obtain a high yield of bioactive compounds while requiring less water for the microorganism’s growth. A number of scientific studies evinced an increase in flavonoids [...] Read more.
Industrial food waste has potential for generating income from high-added-value compounds through fermentation. Solid-state fermentation is promising to obtain a high yield of bioactive compounds while requiring less water for the microorganism’s growth. A number of scientific studies evinced an increase in flavonoids or phenolics from fruit or vegetable waste and bioactive peptides from cereal processing residues and whey, a major waste of the dairy industry. Livestock, fish, or shellfish processing by-products (skin, viscera, fish scales, seabass colon, shrimp waste) also has the possibility of generating antioxidant peptides, hydrolysates, or compounds through fermentation. These bioactive compounds (phenolics, flavonoids, or antioxidant peptides) resulting from bacterial or fungal fermentation are also capable of inhibiting the growth of commonly occurring food spoilage fungi and can be used as natural preservatives. Despite the significant release or enhancement of antioxidant compounds through by-products fermentation, the surface areas of large-scale bioreactors and flow patterns act as constraints in designing a scale-up process for improved efficiency. An in-process purification method can also be the most significant contributing factor for raising the overall cost. Therefore, future research in modelling scale-up design can contribute towards mitigating the discard of high-added-value generating residues. Therefore, in this review, the current knowledge on the use of fermentation to obtain bioactive compounds from food by-products, emphasizing their use as natural preservatives, was evaluated. Full article
(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 3.0)
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