Advances in Microbial Fermentation Processes

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Biological Processes and Systems".

Deadline for manuscript submissions: closed (30 April 2021) | Viewed by 54280

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Co-Guest Editor
National Research Council—Institute of Sciences of Food Production (CNR-ISPA), Via Prov. Lecce-Monteroni, 73100 Lecce, Italy
Interests: beer; wine; agri-food fermentations; microbial starters; microbial biomass production
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Dear Colleagues,

In the food sector, fermentation processes have been the object of great interest in regards to enhancing the yield, the quality, and the safety of the final product. The microbial fermentation has been traditionally used to produce foods denoted by prolonged shelf life and digestibility. The benefits extended to human health by fermented foods are expressed either directly through the interactions of ingested live microorganisms with the host (probiotic effect) or indirectly as the result of the ingestion of microbial metabolites synthesized during fermentation (biogenic effect). Moreover, several beneficial microbes can inhibit pathogens/spoilers growth and degrade toxins.

Several novel microbial-based biotechnological solutions have been recorded and continuous explorations of microbial diversity are being carried out worldwide. In addition, most recently, fermentation has been considered a sustainable approach for maximizing the utilization of bioresources to address the recent global food crisis. For example, several microbial-base bioconversions have been proposed for the production of enzymes, vitamins, antioxidants, biofuels, feeds, antimicrobial molecules, and other bioactive chemicals, also exploiting agro-industrial wastes.

We encourage the presentation of high-quality contributions (original research articles or review papers) providing innovations in microbial fermentative processes, including improvements of quality/safety of fermented foods and beverages, production of high added-values products, and valorization/recovery of agro-food wastes.

Dr. Maria Tufariello
Guest Editor
Dr. Francesco Grieco
Co-Guest Editor

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Keywords

  • Fermented foods
  • fermented beverages
  • bioactive compounds
  • volatile compounds
  • probiotics
  • nutrients
  • food safety
  • food processing
  • biotechnologies
  • agro-food wastes
  • microbial bio-productions

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Published Papers (13 papers)

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Editorial

Jump to: Research, Review

3 pages, 192 KiB  
Editorial
Advances in Microbial Fermentation Processes
by Maria Tufariello and Francesco Grieco
Processes 2021, 9(8), 1371; https://doi.org/10.3390/pr9081371 - 5 Aug 2021
Viewed by 1648
Abstract
In the food sector, fermentation processes have been the object of great interest in regard to enhancing the yield, the quality, and the safety of the final product [...] Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)

Research

Jump to: Editorial, Review

20 pages, 1868 KiB  
Article
Bacterial Succession Pattern during the Fermentation Process in Whole-Plant Corn Silage Processed in Different Geographical Areas of Northern China
by Chao Wang, Hongyan Han, Lin Sun, Na Na, Haiwen Xu, Shujuan Chang, Yun Jiang and Yanlin Xue
Processes 2021, 9(5), 900; https://doi.org/10.3390/pr9050900 - 20 May 2021
Cited by 9 | Viewed by 2207
Abstract
Whole-plant corn silage is a predominant forage for livestock that is processed in Heilongjiang province (Daqing city and Longjiang county), Inner Mongolia Autonomous Region (Helin county and Tumet Left Banner) and Shanxi province (Taigu and Shanyin counties) of North China; it was sampled [...] Read more.
Whole-plant corn silage is a predominant forage for livestock that is processed in Heilongjiang province (Daqing city and Longjiang county), Inner Mongolia Autonomous Region (Helin county and Tumet Left Banner) and Shanxi province (Taigu and Shanyin counties) of North China; it was sampled at 0, 5, 14, 45 and 90 days after ensiling. Bacterial community and fermentation quality were analysed. During fermentation, the pH was reduced to below 4.0, lactic acid increased to above 73 g/kg DM (p < 0.05) and Lactobacillus dominated the bacterial community and had a reducing abundance after 14 days. In the final silages, butyric acid was not detected, and the contents of acetic acid and ammonia nitrogen were below 35 g/kg DM and 100 g/kg total nitrogen, respectively. Compared with silages from Heilongjiang and Inner Mongolia, silages from Shanxi contained less Lactobacillus and more Leuconostoc (p < 0.05), and had a separating bacterial community from 14 to 90 days. Lactobacillus was negatively correlated with pH in all the silages (p < 0.05), and positively correlated with lactic and acetic acid in silages from Heilongjiang and Inner Mongolia (p < 0.05). The results show that the final silages had satisfactory fermentation quality. During the ensilage process, silages from Heilongjiang and Inner Mongolia had similar bacterial-succession patterns; the activity of Lactobacillus formed and maintained good fermentation quality in whole-plant corn silage. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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16 pages, 2171 KiB  
Article
Microbial Communities, Metabolites, Fermentation Quality and Aerobic Stability of Whole-Plant Corn Silage Collected from Family Farms in Desert Steppe of North China
by Chao Wang, Lin Sun, Haiwen Xu, Na Na, Guomei Yin, Sibo Liu, Yun Jiang and Yanlin Xue
Processes 2021, 9(5), 784; https://doi.org/10.3390/pr9050784 - 29 Apr 2021
Cited by 10 | Viewed by 2270
Abstract
Whole-plant corn silages on family farms were sampled in Erdos (S1), Baotou (S2), Ulanqab (S3), and Hohhot (S4) in North China, after 300 d of ensiling. The microbial communities, metabolites, and aerobic stability were assessed. Lactobacillusbuchneri, Acinetobacter johnsonii, and unclassified [...] Read more.
Whole-plant corn silages on family farms were sampled in Erdos (S1), Baotou (S2), Ulanqab (S3), and Hohhot (S4) in North China, after 300 d of ensiling. The microbial communities, metabolites, and aerobic stability were assessed. Lactobacillusbuchneri, Acinetobacter johnsonii, and unclassified Novosphingobium were present at greater abundances than others in S2 with greater bacterial diversity and metabolites. Lactobacillus buchneri, Lactobacillus parafarraginis, Lactobacillus kefiri, and unclassified Lactobacillus accounted for 84.5%, and 88.2%, and 98.3% of bacteria in S1, S3, and S4, respectively. The aerobic stability and fungal diversity were greater in S1 and S4 with greater abundances of unclassified Kazachstania, Kazachstania bulderi, Candida xylopsoci, unclassified Cladosporium, Rhizopus microspores, and Candida glabrata than other fungi. The abundances of unclassified Kazachstania in S2 and K. bulderi in S3 were 96.2% and 93.6%, respectively. The main bacterial species in S2 were L. buchneri, A. johnsonii, and unclassified Novosphingobium; Lactobacillus sp. dominated bacterial communities in S1, S3, and S4. The main fungal species in S1 and S4 were unclassified Kazachstania, K. bulderi, C. xylopsoci, unclassified Cladosporium, R. microspores, and C. glabrata; Kazachstania sp. dominated fungal communities in S2 and S3. The high bacterial diversity aided the accumulation of metabolites, and the broad fungal diversity improved the aerobic stability. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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11 pages, 263 KiB  
Article
Synbiotic Fermented Milk with Double Fortification (Fe-Zn) as a Strategy to Address Stunting: A Randomized Controlled Trial among Children under Five in Yogyakarta, Indonesia
by Siti Helmyati, Karina Muthia Shanti, Fahmi Tiara Sari, Martha Puspita Sari, Dominikus Raditya Atmaka, Rio Aditya Pratama, Maria Wigati, Setyo Utami Wisnusanti, Fatma Zuhrotun Nisa’ and Endang Sutriswati Rahayu
Processes 2021, 9(3), 543; https://doi.org/10.3390/pr9030543 - 19 Mar 2021
Cited by 7 | Viewed by 3511
Abstract
Stunting is one of the public health problems that has yet to be solved in Indonesia. This study developed synbiotic fermented milk with iron and zinc fortification that was then tested in a clinical setting. The product was made from skimmed milk and [...] Read more.
Stunting is one of the public health problems that has yet to be solved in Indonesia. This study developed synbiotic fermented milk with iron and zinc fortification that was then tested in a clinical setting. The product was made from skimmed milk and fructooligosaccharides (FOS) and fermented with Lactobacillus plantarum. A sample of 94 stunted children under five years old were randomly assigned to intervention or control groups. The intervention group received double-fortified synbiotic milk, while the control group drank non-fortified milk. After three months, the number of normal children in both groups, according to weight- or height-for-age z-score category, was found to be increasing. However, the difference between the two groups was not significant (p > 0.05). The study suggests that fermented milk may have a good effect on child growth. Further research is needed to deepen the potency of synbiotic fermented milk for stunted children. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
16 pages, 1770 KiB  
Article
Impact of Altered Trehalose Metabolism on Physiological Response of Penicillium chrysogenum Chemostat Cultures during Industrially Relevant Rapid Feast/Famine Conditions
by Xinxin Wang, Jiachen Zhao, Jianye Xia, Guan Wang, Ju Chu and Yingping Zhuang
Processes 2021, 9(1), 118; https://doi.org/10.3390/pr9010118 - 7 Jan 2021
Cited by 5 | Viewed by 2039
Abstract
Due to insufficient mass transfer and mixing issues, cells in the industrial-scale bioreactor are often forced to experience glucose feast/famine cycles, mostly resulting in reduced commercial metrics (titer, yield and productivity). Trehalose cycling has been confirmed as a double-edged sword in the Penicillium [...] Read more.
Due to insufficient mass transfer and mixing issues, cells in the industrial-scale bioreactor are often forced to experience glucose feast/famine cycles, mostly resulting in reduced commercial metrics (titer, yield and productivity). Trehalose cycling has been confirmed as a double-edged sword in the Penicillium chrysogenum strain, which facilitates the maintenance of a metabolically balanced state, but it consumes extra amounts of the ATP responsible for the repeated breakdown and formation of trehalose molecules in response to extracellular glucose perturbations. This loss of ATP would be in competition with the high ATP-demanding penicillin biosynthesis. In this work, the role of trehalose metabolism was further explored under industrially relevant conditions by cultivating a high-yielding Penicillium chrysogenum strain, and the derived trehalose-null strains in the glucose-limited chemostat system where the glucose feast/famine condition was imposed. This dynamic feast/famine regime with a block-wise feed/no feed regime (36 s on, 324 s off) allows one to generate repetitive cycles of moderate changes in glucose availability. The results obtained using quantitative metabolomics and stoichiometric analysis revealed that the intact trehalose metabolism is vitally important for maintaining penicillin production capacity in the Penicillium chrysogenum strain under both steady state and dynamic conditions. Additionally, cells lacking such a key metabolic regulator would become more sensitive to industrially relevant conditions, and are more able to sustain metabolic rearrangements, which manifests in the shrinkage of the central metabolite pool size and the formation of ATP-consuming futile cycles. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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17 pages, 4298 KiB  
Article
Microbial Production and Enzymatic Biosynthesis of γ-Aminobutyric Acid (GABA) Using Lactobacillus plantarum FNCC 260 Isolated from Indonesian Fermented Foods
by Ida Bagus Agung Yogeswara, Suwapat Kittibunchakul, Endang Sutriswati Rahayu, Konrad J. Domig, Dietmar Haltrich and Thu Ha Nguyen
Processes 2021, 9(1), 22; https://doi.org/10.3390/pr9010022 - 24 Dec 2020
Cited by 32 | Viewed by 4164
Abstract
In the present study, we isolated and screened thirty strains of GABA (γ-aminobutyric acid)-producing lactic acid bacteria (LAB) from traditional Indonesian fermented foods. Two strains were able to convert monosodium glutamate (MSG) to GABA after 24 h of cultivation at 37 °C based [...] Read more.
In the present study, we isolated and screened thirty strains of GABA (γ-aminobutyric acid)-producing lactic acid bacteria (LAB) from traditional Indonesian fermented foods. Two strains were able to convert monosodium glutamate (MSG) to GABA after 24 h of cultivation at 37 °C based on thin layer chromatography (TLC) screening. Proteomic identification and 16S rDNA sequencing using MALDI-TOF MS identified the strain as Lactobacillus plantarum designated as L. plantarum FNCC 260 and FNCC 343. The highest yield of GABA production obtained from the fermentation of L. plantarum FNCC 260 was 809.2 mg/L of culture medium after 60 h of cultivation. The supplementation of 0.6 mM pyridoxal 5’-phosphate (PLP) and 0.1 mM pyridoxine led to the increase in GABA production to 945.3 mg/L and 969.5 mg/L, respectively. The highest GABA production of 1226.5 mg/L of the culture medium was obtained with 100 mM initial concentration of MSG added in the cultivation medium. The open reading frame (ORF) of 1410 bp of the gadB gene from L. plantarum FNCC 260 encodes 469 amino acids with a calculated molecular mass of 53.57 kDa. The production of GABA via enzymatic conversion of monosodium glutamate (MSG) using purified recombinant glutamate decarboxylase (GAD) from L. plantarum FNCC 260 expressed in Escherichia coli was found to be more efficient (5-fold higher within 6 h) than the production obtained from fermentation. L. plantarum FNCC 260 could be of interest for the synthesis of GABA. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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14 pages, 2179 KiB  
Article
Antifungal Effect of Volatile Organic Compounds from Bacillus velezensis CT32 against Verticillium dahliae and Fusarium oxysporum
by Xinxin Li, Xiuhong Wang, Xiangyuan Shi, Baoping Wang, Meiping Li, Qi Wang and Shengwan Zhang
Processes 2020, 8(12), 1674; https://doi.org/10.3390/pr8121674 - 18 Dec 2020
Cited by 43 | Viewed by 3815
Abstract
The present study focuses on the inhibitory effect of volatile metabolites released by Bacillus velezensis CT32 on Verticillium dahliae and Fusarium oxysporum, the causal agents of strawberry vascular wilt. The CT32 strain was isolated from maize straw compost tea and identified as [...] Read more.
The present study focuses on the inhibitory effect of volatile metabolites released by Bacillus velezensis CT32 on Verticillium dahliae and Fusarium oxysporum, the causal agents of strawberry vascular wilt. The CT32 strain was isolated from maize straw compost tea and identified as B. velezensis based on 16S rRNA gene sequence analysis. Bioassays conducted in sealed plates revealed that the volatile organic compounds (VOCs) produced by the strain CT32 possessed broad-spectrum antifungal activity against eight phytopathogenic fungi. The volatile profile of strain CT32 was obtained by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). A total of 30 volatile compounds were identified, six of which have not previously been detected in bacteria or fungi: (Z)-5-undecene, decyl formate, 2,4-dimethyl-6-tert-butylphenol, dodecanenitrile, 2-methylpentadecane and 2,2’,5,5’-tetramethyl-1,1’-biphenyl. Pure compounds were tested in vitro for their inhibitory effect on the mycelial growth of V. dahliae and F. oxysporum. Decanal, benzothiazole, 3-undecanone, 2-undecanone, 2-undecanol, undecanal and 2,4-dimethyl-6-tert-butylphenol showed high antifungal activity, with benzothiazole and 2,4-dimethyl-6-tert-butylphenol being the most potent compounds. These results indicate that the VOCs produced by B. velezensis CT32 have the potential to be used as a biofumigant for management of vascular wilt pathogens. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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26 pages, 4171 KiB  
Article
High Cell Density Cultivation of Saccharomyces cerevisiae with Intensive Multiple Sequential Batches Together with a Novel Technique of Fed-Batch at Cell Level (FBC)
by Kwanruthai Malairuang, Morakot Krajang, Jatuporn Sukna, Krongchan Rattanapradit and Saethawat Chamsart
Processes 2020, 8(10), 1321; https://doi.org/10.3390/pr8101321 - 21 Oct 2020
Cited by 31 | Viewed by 11716
Abstract
High cell density cultivation (HCDC) is developed for the production of microbial biomasses and their products. They must be produced from high concentrations of substrate, e.g., glucose or sucrose. In batch culture, a high concentration of those sugars >40–50% (w/v) cannot [...] Read more.
High cell density cultivation (HCDC) is developed for the production of microbial biomasses and their products. They must be produced from high concentrations of substrate, e.g., glucose or sucrose. In batch culture, a high concentration of those sugars >40–50% (w/v) cannot efficiently be utilized because of a dissolved O2 limitation causing the Crabtree effect that produces toxic by-products, i.e., ethanol and/or acetate, that inhibit cell growth. To prevent this effect, the HCDC is conducted with the fed-batch strategies. However, it has many disadvantages, i.e., complicated operations. To overcome those problems, this study was designed to use a new, efficient C-source (carbon source) substrate, namely dextrin, an oligomer of glucose. It can be utilized by yeast at a very high concentration of ~100 g/L although using just batch cultivation. As it is gradually hydrolyzed to release glucose molecules and gradually assimilated into the cells as “fed-batch at the cell level” (FBC), it prevents the yeast cell system from undergoing the Crabtree effect. In this research, the types of medium, the types of sugar compared with dextrin, and the concentrations of yeast extract (YE) were studied. The batch production medium (BPM) with dextrin and YE performed very good results. The concentrations of dextrin for yeast cultivation were studied in the aerobic batch 5-L bioreactors. Its optimum concentration was at 90 g/L with 9 g/L of YE in 3× BPM. It was operated at 3 W/kg energy dissipation rate per unit mass (ε¯T) and 3 vvm airflow rate. Further, the intensive multiple sequential batch (IMSB) technique of high intensities of agitation speed and airflow was developed to achieve higher yield and productivity. The maximum values of cell biomass, specific growth rate, yield coefficient, productivity, and efficiency were at 55.17 g/L, 0.21 h−1, 0.54 g/g, 2.30 g/L/h, and 98.18%, respectively. The studies of cell growth kinetics, biochemical engineering mass balances, and fluid dynamics for the design of impeller speeds of the 5-L bioreactors during the cultivations of yeast using dextrin at the high concentrations were successful. The results can be used for the scale-up of bioreactor for the industrial production of yeast cell biomass at high concentrations. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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17 pages, 4131 KiB  
Article
Morphological Differentiation of Streptomyces clavuligerus Exposed to Diverse Environmental Conditions and Its Relationship with Clavulanic Acid Biosynthesis
by Jeferyd Yepes-García, Carlos Caicedo-Montoya, Laura Pinilla, León F. Toro and Rigoberto Ríos-Estepa
Processes 2020, 8(9), 1038; https://doi.org/10.3390/pr8091038 - 25 Aug 2020
Cited by 7 | Viewed by 3928
Abstract
Clavulanic acid (CA) is a potent inhibitor of class A β-lactamase enzymes produced by Streptomyces clavuligerus (S. clavuligerus) as a defense mechanism. Due to its industrial interest, the process optimization is under continuous investigation. This work aimed at identifying the potential relationship that [...] Read more.
Clavulanic acid (CA) is a potent inhibitor of class A β-lactamase enzymes produced by Streptomyces clavuligerus (S. clavuligerus) as a defense mechanism. Due to its industrial interest, the process optimization is under continuous investigation. This work aimed at identifying the potential relationship that might exist between S. clavuligerus ATCC 27064 morphology and CA biosynthesis. For this, modified culture conditions such as source, size, and age of inoculum, culture media, and geometry of fermentation flasks were tested. We observed that high density spore suspensions (1 × 107 spores/mL) represent the best inoculum source for S. clavuligerus cell suspension culture. Further, we studied the life cycle of S. clavuligerus in liquid medium, using optic, confocal, and electron microscopy; results allowed us to observe a potential relationship that might exist between the accumulation of CA and the morphology of disperse hyphae. Reactor geometries that increase shear stress promote smaller pellets and a quick disintegration of these in dispersed secondary mycelia, which begins the pseudosporulation process, thus easing CA accumulation. These outcomes greatly contribute to improving the understanding of antibiotic biosynthesis in the Streptomyces genus. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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7 pages, 223 KiB  
Article
Influence of Different Smoking Procedures on Polycyclic Aromatic Hydrocarbons Formation in Traditional Dry Sausage Hercegovačka kobasica
by Krešimir Mastanjević, Brankica Kartalović, Leona Puljić, Dragan Kovačević and Kristina Habschied
Processes 2020, 8(8), 918; https://doi.org/10.3390/pr8080918 - 2 Aug 2020
Cited by 8 | Viewed by 2117
Abstract
The concentrations of 16 polycyclic aromatic hydrocarbons (PAH) in smoked dry sausage Hercegovačka kobasica were investigated. The sausages were stuffed in two different casings (collagen and natural) and smoked in traditional and industrial smokehouses. The highest concentration of PAH 16 were detected in [...] Read more.
The concentrations of 16 polycyclic aromatic hydrocarbons (PAH) in smoked dry sausage Hercegovačka kobasica were investigated. The sausages were stuffed in two different casings (collagen and natural) and smoked in traditional and industrial smokehouses. The highest concentration of PAH 16 were detected in sausages in natural casings smoked in the traditional manner. The samples smoked in the industrial chamber stuffed in collagen casing showed the lowest PAH 16 content. The content of PAH 4 in sausage smoked in the traditional way and stuffed in natural casing averaged 24.46 µg/kg, which is more the double of maximum prescribed concentration of 12 µg/kg. The concentration of cancerogenic benzo[a]pyrene averaged 7.79 µg/kg in sausage stuffed in natural casing and smoked in the traditional way, which is almost four times the legislative prescribed values (2 µg/kg). Sausage smoked in the traditional manner and stuffed in collagen casing showed lower values for PAH 4 (13.88 µg/kg) and benzo[a]pyrene (4.97 µg/kg), but these values were also above the legislative prescribed values. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
16 pages, 2138 KiB  
Article
Intensive Multiple Sequential Batch Simultaneous Saccharification and Cultivation of Kluyveromyces marxianus SS106 Thermotolerant Yeast Strain for Single-Step Ethanol Fermentation from Raw Cassava Starch
by Kwanruthai Malairuang, Morakot Krajang, Rapeepong Rotsattarat and Saethawat Chamsart
Processes 2020, 8(8), 898; https://doi.org/10.3390/pr8080898 - 27 Jul 2020
Cited by 7 | Viewed by 3293
Abstract
We developed the intensive multiple sequential batch simultaneous saccharification and cultivation of the selected thermotolerant yeast strain for single-step ethanol production. The selection and high-cell-density inoculum production of thermotolerant yeast able to produce ethanol under the optimal conditions for single-step ethanol fermentation has [...] Read more.
We developed the intensive multiple sequential batch simultaneous saccharification and cultivation of the selected thermotolerant yeast strain for single-step ethanol production. The selection and high-cell-density inoculum production of thermotolerant yeast able to produce ethanol under the optimal conditions for single-step ethanol fermentation has become a necessity. In this study, the newly isolated Kluyveromyces marxianus SS106 could tolerate high temperatures (35–45 °C) and grow under a wide range of pH values (3.0–5.5), which are the optimum conditions of raw cassava starch hydrolyzing enzyme used in single-step ethanol fermentation. The high-cell-density concentration of K. marxianus SS106 was produced by a single batch and an intensive multiple sequential batch process in a 5-L stirred tank bioreactor using the simultaneous saccharification and cultivation (SSC) method. The single SSC process yielded the yeast cell biomass at a concentration of 39.30 g/L with a productivity of 3.28 g/L/h and a specific growth rate of 0.49 h−1. However, the yeast cell density concentration was higher in the intensive multiple sequential batch SSC than in the single batch process. This process yielded yeast cell biomass at concentrations of 36.09–45.82 g/L with productivities of 3.01–3.82 g/L/h and specific growth rates of 0.29–0.44 h−1 in the first six batch cycle. The results suggested that the intensive multiple sequential batch simultaneous saccharification and cultivation of K. marxianus SS106 would be a promising process for high-cell-density yeast production for use as the inoculum in single-step ethanol fermentation. Furthermore, we also experimented with single-step ethanol production from raw cassava starch by K. marxianus SS106 in a 5-L stirred tank fermenter. This produced ethanol at a concentration of 61.72 g/L with a productivity of 0.86 g/L/h. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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Review

Jump to: Editorial, Research

13 pages, 758 KiB  
Review
Quantification of Volatile Compounds in Wines by HS-SPME-GC/MS: Critical Issues and Use of Multivariate Statistics in Method Optimization
by Sandra Pati, Maria Tufariello, Pasquale Crupi, Antonio Coletta, Francesco Grieco and Ilario Losito
Processes 2021, 9(4), 662; https://doi.org/10.3390/pr9040662 - 9 Apr 2021
Cited by 31 | Viewed by 5438
Abstract
The aim of this review is to explore and discuss the two main aspects related to a HeadSpace Solid Phase Micro-Extraction Gas-Chromatography/Mass-Spectrometry (HS-SPME-GC/MS) quantitative analysis of volatile compounds in wines, both being fundamental to obtain reliable data. In the first section, recent advances [...] Read more.
The aim of this review is to explore and discuss the two main aspects related to a HeadSpace Solid Phase Micro-Extraction Gas-Chromatography/Mass-Spectrometry (HS-SPME-GC/MS) quantitative analysis of volatile compounds in wines, both being fundamental to obtain reliable data. In the first section, recent advances in the use of multivariate optimization approaches during the method development step are described with a special focus on factorial designs and response surface methodologies. In the second section, critical aspects related to quantification methods are discussed. Indeed, matrix effects induced by the complexity of the volatile profile and of the non-volatile matrix of wines, potentially differing between diverse wines in a remarkable extent, often require severe assumptions if a reliable quantification is desired. Several approaches offering different levels of data reliability including internal standards, model wine calibration, a stable isotope dilution analysis, matrix-matched calibration and standard addition methods are reported in the literature and are discussed in depth here. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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25 pages, 4073 KiB  
Review
Fermentation of Organic Residues to Beneficial Chemicals: A Review of Medium-Chain Fatty Acid Production
by Panagiota Stamatopoulou, Juliet Malkowski, Leandro Conrado, Kennedy Brown and Matthew Scarborough
Processes 2020, 8(12), 1571; https://doi.org/10.3390/pr8121571 - 28 Nov 2020
Cited by 36 | Viewed by 6414
Abstract
Medium-chain fatty acids (MCFAs) have a variety of uses in the production of industrial chemicals, food, and personal care products. These compounds are often produced through palm refining, but recent work has demonstrated that MCFAs can also be produced through the fermentation of [...] Read more.
Medium-chain fatty acids (MCFAs) have a variety of uses in the production of industrial chemicals, food, and personal care products. These compounds are often produced through palm refining, but recent work has demonstrated that MCFAs can also be produced through the fermentation of complex organic substrates, including organic waste streams. While “chain elongation” offers a renewable platform for producing MCFAs, there are several limitations that need to be addressed before full-scale implementation becomes widespread. Here, we review the history of work on MCFA production by both pure and mixed cultures of fermenting organisms, and the unique metabolic features that lead to MCFA production. We also offer approaches to address the remaining challenges and increase MCFA production from renewable feedstocks. Full article
(This article belongs to the Special Issue Advances in Microbial Fermentation Processes)
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