Traditional Fermentation Research Articles

Improving dairy manure hydrolysis and acidification through microbial community restructuring by adaptation to hyperthermophilic conditions

Dairy manure (DM) contributes significantly to greenhouse gas emissions and ecosystem degradation, yet its resistance to biodegradation hinders widespread bioprocessing applications. Lignocellulosic materials in DM pose a particular challenge because of their recalcitrance. Bioprocessing under hyperthermophilic (≥70 °C) conditions potentially offers an advantage over traditional fermentation temperatures due to enhanced activity of enzymes and the kinetics of enzymatic reactions. This can lead to a higher conversion rate and a greater extent of biomass hydrolysis and acidification. To test the validity of this hypothesis, the current study evaluated the efficacy of anaerobic hydrolysis and acidogenic fermentation of DM under mesophilic, thermophilic, and hyperthermophilic conditions. All inocula were adapted to corresponding temperatures but were derived from the same mesophilic source. Hyperthermophilic conditions resulted in superior DM hydrolysis efficiency (53%) compared to mesophilic (34%) and thermophilic (42%) conditions. The hyperthermophilic environment was particularly favorable to the decomposition of crude proteins and hemicellulose, which were reduced by 64% and 54%, respectively. Furthermore, hyperthermophilic fermentation also yielded the highest volatile fatty acid (VFA) production rate of 460 mg/L/day during the first four days, representing improvements of 50% and 90% over mesophilic and thermophilic conditions. In part, this was attributed to the enhanced production of branched-chain VFAs, including an increase of 6–10% in isobutyric acid and 12–13% in isovaleric acid. At hyperthermophilic conditions, however, there was no accumulation of VFAs during the days 5–8 of fermentation, which could be due to acetate conversion by the syntrophic acetate-oxidizing bacteria. A considerable gain in hydrolysis efficiency and VFA production rate were accompanied by a reduction in microbial diversity, which suggests that hyperthermophilic temperature is a favorable environment for the selection of organisms with enhanced DM hydrolysis and fermentation capabilities. A significantly increased relative abundance of xylanolytic Caldicoprobacter (23% of population) and proteolytic Thermovirga (9% of population) could be the major contributors to improved decomposition of hemicellulose and protein. As revealed by the techno-economic analysis, acidogenic fermentation of DM at 70 °C and a retention period of 4 days provides the greatest positive net present value, highest internal rate of return of 9.2%, and shortest investment payback period of 9 years. This study demonstrates that hyperthermophilic conditions enable superior deconstruction and bioconversion of lignocellulose-containing biomass into VFAs under reduced retention times, offering a promising approach for improving DM management and generating bioproducts.

Bioconversion of ricinoleic acid to (R)-γ-decalactone by Clavispora lusitaniae YJ26 cells in an ionic liquid–containing biphasic fermentation system

Microbial production of chiral γ-decalactone has received considerable attention due to its high market value. However, the inhibition of substrates and products on microorganisms has significantly limited the production of chiral γ-decalactone. In this study, a green biphasic fermentation system containing 1-butyl-3-methylimidazolium tetrafluoroborate ([C4MIM]PF6) was developed to increase the synthesis of (R)-γ-decalactone from ricinoleic acid catalyzed by Clavispora lusitaniae YJ26. Under optimal conditions, the titer of γ-decalactone obtained using the biphasic system reached 2.04 g/L, which is 2.4 times that of the traditional aqueous fermentation system, and showed high enantioselectivity (e.e.> 99.0%). Fluorescence microscopy and flow cytometry results demonstrated that the addition of [C4MIM]PF6 significantly alleviated the damage of substrate and product to cell membrane and improved cell viability, thus increasing the titer of γ-decalactone. Furthermore, comparative transcriptomic analysis results suggested that the improved mechanism may be attributed to the up-regulation of genes associated with cell membrane component synthesis or cell tolerance enhancement. Overall, the experimental results provide valuable insights into the efficient microbial production of chiral decalactone in an ionic liquids–containing biphasic fermentation system.

Comparative analysis of microbial diversity and functional characteristics of low-temperature Daqu from different regions in China

Baijiu is a unique alcoholic beverage in China, prepared through a traditional solid-state fermentation process. Daqu, recognized as the earliest form of crude enzyme preparation, plays a crucial role in determining the quality of Baijiu. Due to the enzymatic process derived from natural fermentation, the differences between regions were expected to occur. To compare regional-difference in microbial diversity and the functional profile of Daqu, metagenomic sequencing, physicochemical analysis, and electronic sensory evaluation were utilized. The results showed that bacteria and fungi were the main microbes in low-temperature Daqu (LTD), and their ratio of abundance was approximately 9:1. Streptomyces (20.27 %) and Bacillus licheniformis (15.28 %) emerged as the most dominant microbes in LTD at the genus and species levels, respectively. The overall microbial communities and functional profiles of Daqu between the two regions exhibited significant differences (P < 0.05). Bacillus licheniformis was significantly enriched in LTD from Taiyuan (P < 0.05) and mainly contributed to the saccharifying power, fermenting power, esterifying power, and liquefying power of LTD, demonstrating its important role in maintaining LTD quality. LTD from Taiyuan had a significantly higher fermenting power, esterifying power, and liquefying power than LTD from Suizhou (P < 0.05). In addition, a higher abundance of genes responsible for lactate production was detected in LTD from Suizhou, whereas genes associated with acetate production were enriched in LTD from Taiyuan. Collectively, these findings indicated that lactic acid bacteria may play a more important role in LTD from Suizhou, whereas acetate-producing bacteria may have a greater contribution to LTD from Taiyuan. This study provides a reference for microbial regulation during the production process of Daqu, and control of quality and traceability of the origin of Daqu.

Physicochemical, volatiles, non-volatiles, and microbial dynamics in dried versus traditional fresh red pepper paste fermentation: A comparative study

The utilization of dried red peppers (DRPs) in fermented red pepper paste creation serves as a solution to the season-dependent availability of fresh red peppers (FRPs). Nevertheless, the current understanding of the fermentation disparities between DRPs and FRPs is limited, posing challenges to DRPs application in red pepper paste manufacturing. This study conducted a side-by-side analysis of physicochemical indicators, volatiles and non-volatiles, and microbial composition within DRPs and FRPs during fermentation, deploying a comprehensive multi-omics technique. The study results signified that after two weeks of fermentation, pH levels were significantly heightened (p < 0.05) in FRPs than in DRPs, with total acid presenting an opposite trend. Concurrently, total flavonoid content and the a* value were considerably elevated in FRPs (p < 0.05) during the entire fermentation process. Furthermore, the drying process led to substantial changes (p < 0.05) in red pepper metabolites, with higher total volatiles and non-volatiles found in FRPs throughout fermentation. The PLS-DA modeling indicated that 20 volatiles and 37 non-volatiles were screened as differential metabolites between the two pastes, respectively. The microbial composition analysis showed a similar fungal population in both DRPs and FRPs during fermentation, but drying significantly altered the bacterial composition, resulting in Weissella and Ligilactobacillus becoming dominant post-fermentation, whereas Pantoea and Ligilactobacillus dominated in DRPs paste. This study enriches our understanding of the fermentation process using various raw materials and paves the way for the development of DRPs-based red pepper paste that can be produced year-round.

Inhibition of porcine origin Klebsiella pneumoniae capsular polysaccharide and immune escape by BY3 compounded traditional Chinese medicine residue fermentation broth

Klebsiella pneumoniae (K. pneumoniae) is a gram-negative conditionally pathogenic bacterium that causes disease primarily in immunocompromised individuals. Recently, highly virulent K. pneumoniae strains have caused severe disease in healthy individuals, posing significant challenges to global infection control. Capsular polysaccharide (CPS), a major virulence determinant of K. pneumoniae, protects the bacteria from being killed by the host immune system, suggesting an urgent need for the development of drugs to prevent or treat K. pneumoniae infections. In this study, BY3 compounded traditional Chinese medicine residue (TCMR) was carried out using Lactobacillus rhamnosus as a fermentation strain, and BY3 compounded TCMR fermentation broth (BY3 fermentation broth) was obtained. The transcription of K. pneumoniae CPS-related biosynthesis genes after treatment with BY3 fermentation broth was detected using quantitative real-time polymerase chain reaction. The effects of BY3 fermentation broth on K. pneumoniae serum killing, macrophage phagocytosis, complement deposition and human β-defensin transcription were investigated. The therapeutic effect of BY3 fermentation broth on K. pneumoniae-infected mice was also observed, and the major active components of BY3 fermentation broth were analysed via LC‒MS analysis, network pharmacology, and molecular docking. The results showed that BY3 fermentation broth inhibited K. pneumoniae CPS production and downregulated transcription of CPS-related biosynthesis genes, which weakened bacterial resistance to serum killing and phagocytosis, while promoting bacterial surface complement C3 deposition and human β-defensin expression. BY3 fermentation broth demonstrated safety and therapeutic effects in vivo and in vitro, restoring body weight and visceral indices, significantly reducing the organ bacterial load and serum cytokine levels, and alleviating pathological organ damage in mice. In addition, three natural compounds—oleanolic acid, quercetin, and palmitoleic acid—were identified as the major active components in the BY3 fermentation broth. Therefore, BY3 fermentation broth may be a promising strategy for the prevention or treatment of K. pneumoniae infections.

Physicochemical, Functional, Antioxidant, Pasting and FT-IR Spectroscopic Properties of Fermented Acorns and Sorghum Using Traditional Algerian Processes

The fermentation of acorns and sorghum is an ancient practice among the inhabitants of northeastern Algeria. This study aimed to establish the traditional fermentation processes of acorns and sorghum through a regional survey conducted in Algeria. Additionally, it investigated the impact of fermentation on the physicochemical, functional, antioxidant, and pasting properties, as well as the FT-IR spectroscopic profiles of the flours derived from these fermented materials. Characteristics of fermented sorghum and acorn flours were compared with those of non-fermented flours. The study included a survey that was carried out in Algeria at the regional level to establish the traditional processes for fermented acorns and sorghum. The key findings reveal the existence of two production methods: the first, the oldest, involves fermentation in underground pits called Matmor, while the second, more recent, is conducted outside the Matmor. Most manufacturers employed the new process outside of the Matmor, usually in various sized and shaped containers to meet market demand. Acorns and sorghum flour, obtained by drying and grinding fermented acorns and fermented sorghum grains according to the process carried out outside the Matmor, are characterized by a unique biochemical, functional, and structural composition. Detailed analysis of the flours showed a significant decrease in their physicochemical properties after fermentation, with a simultaneous overall increase in antioxidant activity. Moreover, FT-IR spectroscopy suggests that fermentation differentially affects protein secondary structure and starch crystallinity.

Repercussions of Lactiplantibacillus plantarum HYY‐DB9 and Levilactobacillus brevis GIM 1.773 on the degradation of nitrite, volatile compounds, and sensory assessment of traditional Chinese paocai

SummaryPaocai, as one of the most widely consumed traditional fermented foods in China, is dominated by lactic acid bacteria (LAB), which exert a significant influence on the dynamics of metabolites, microecological changes, and sensory quality. In this study, five different paocai groups were designed for fermentation using Lactiplantibacillus plantarum HYY‐DB9 (LP), Levilactobacillus brevis GIM 1.773 (LB), a mixture of two LABs (LP + LB), pasteurisation (PST), and natural fermentation (NF). Nitrite content, pH, titratable acidity, viable cell counts (LAB and yeasts), metabolites (organic acids and volatile substances), and sensory evaluation were determined for each group. The results demonstrated that the mixed fermentation with two LABs (LP + LB) significantly reduced nitrite content. Organic acids produced by LAB played a crucial role in the degradation process, particularly lactic acid which exhibited the most pronounced effect on nitrite degradation. Furthermore, artificial inoculation of LAB fermentation resulted in improved taste and flavour of paocai along with increased production of alcohols, esters, and acids compared to traditional natural fermentation. These findings have important implications for enhancing paocai quality control and managing nitrite content while also providing an excellent fermentation agent for fermented paocai.

Enterococcus avium from a traditional Chinese liquor fermentation system with the potential for the de novo synthesis of GABA

γ-Aminobutyric acid (GABA) is a prevalent nonprotein amino acid with diverse physiological functions, attracting considerable interest in the food industry. However, current GABA-producing strains require glutamate as a substrate for synthesis. Probiotics capable of de novo GABA synthesis using sugars without glutamate are crucial for developing novel foods. This study employed a pH indicator method to selectively screen for GABA-producing bacteria. Nineteen strains with fermentation liquid pH greater than 5 were obtained, all demonstrated the ability to synthesize GABA from Daqu. Among these strains, Enterococcus (E.) avium GL1 stood out for its high GABA production capacity, reaching 9.8 g/L when utilizing glucose for de novo GABA synthesis without monosodium glutamate (MSG). E. avium GL1 exhibited robust viability in challenging environments, maintaining stability in simulated gastric and intestinal fluids. As a potentially probiotic strain, E. avium GL1 achieved remarkable GABA production of 206.84 g/L with a production efficiency of 2.87 g/L/h, facilitated by automatic pH control during fermentation through continuous addition of glucose and MSG addition. This exceptional result represents the highest GABA production reported for E. avium, highlighting its significant potential for the development of innovative functional foods.

Biofunctional attributes and storage study of milk fermented by Enterococcus italicus

Lactic acid bacteria are probiotics in the intestines and have been widely used as natural antioxidants in the food industry. In this study, Enterococcus italicus FM5 with strong antioxidant ability was isolated from fresh milk. The safety evaluation showed that E. italicus FM5 was sensitive to ampicillin, chloramphenicol, erythromycin, vancomycin, rifampicin, and tetracycline, and was not hemolytic. Meanwhile, the whole genome information and biofunctional attributes of this strain were determined and analyzed. Subsequently, E. italicus FM5 was co-cultured with traditional yogurt starters (Streptococcus thermophilus and Lactobacillus bulgaricus) to make fermented milk. The results showed that the addition of E. italicus FM5 could improve the oxygen free radical scavenging ability of the fermented milk, and the scavenging rates of DPPH, ABTS, OH−, and O2− radicals reaching up to 95.54 %, 88.35 %, 93.65 %, and 60.29 %, respectively. Furthermore, the addition of E. italicus FM5 reduced the curd time and improved the water holding capacity of the fermented milk. Besides, the growth of Lb. bulgaricus was significantly promoted when co-cultured with E. italicus FM5, thus the survival cells were increased compared with the traditional fermentation processes. Therefore, this study emphasized the potential to manufacture fermented milk by the co-cultivation of E. italicus with traditional yogurt starters.

Tracking Metabolite Variations during the Degradation of Vegetables in Rice Bran Bed with Intact-State Nuclear Magnetic Resonance Spectroscopy.

Fermentation-a process of compound degradation by microorganisms-is a traditional food processing method utilized worldwide for the long-term preservation of fresh foods. In recent years, fermented foods have gained attention as health foods. Fermentation increases the nutritional value of ingredients, producing complex flavors and aromas. To identify unknown components in fermented foods, it is necessary to analyze compounds and conditions nondestructively and comprehensively. We performed intact-state nuclear magnetic resonance (NMR) spectroscopy using intermolecular single quantum coherence (iSQC) to detect the degradation of vegetables directly and nondestructively. We used two types of vegetables and a rice bran bed (nukazuke), which is used for traditional vegetable fermentation in Japan. Major metabolites such as saccharides, organic acids, and amino acids were identified in iSQC-sliced spectra. Comparing NMR signal intensities during degradation revealed the transition of metabolites characteristic of lactic acid fermentation. A pathway-based network analysis showed pathways involved in amino acid metabolism and lactic acid fermentation. Our analytical approach with intact-state NMR spectroscopy using iSQC demonstrated that it may be effective in other experimental systems, allowing for the evaluation of phenomena that have been conventionally overlooked in their true state.

Effects of Lactic Acid Bacteria on Reducing the Formation of Biogenic Amines and Improving the Formation of Antioxidant Compounds in Traditional African Sourdough Flatbread Fermentation.

This study investigated the safety and functionality of traditional African sourdough flatbread (kisra), based on the content of biogenic amines (BAs) and antioxidant compounds and their improvement using lactic acid bacteria (LAB) species. The primary BAs detected in naturally fermented kisra were tyramine, histamine, putrescine, and cadaverine, with putrescine being the most abundant after baking. In vitro BA production of microorganisms isolated from kisra sourdough revealed that the Enterococcus genus contributed to tyramine accumulation, whereas presumptive yeasts may contribute to putrescine and cadaverine accumulation. The use of LAB species, including Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Levilactobacillus brevis, and Weissella cibaria, significantly reduced putrescine content to less than about 23% of that of naturally fermented kisra, and eliminated tyramine, histamine, and cadaverine formation. Meanwhile, DPPH scavenging activity, total polyphenolic content, and tannin content in naturally fermented kisra were 85.16%, 1386.50 µg/g, and 33.16 µg/g, respectively. The use of LAB species did not affect the DPPH scavenging activity or tannin content but significantly increased the total phenolic content by up to 20% compared to naturally fermented kisra. Therefore, fermentation with LAB starter cultures might be a promising approach to improve the safety related to BAs as well as the functionality of kisra bread.

Difference between traditional brewing technology and mechanized production technology of jiangxiangxing baijiu: Micro ecology of zaopei, physicochemical factors and volatile composition

Mechanized production of Jiangxiangxing Baijiu (JB) stands as a pivotal trend in today’s Baijiu industry. This study, employing high-throughput sequencing and headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC–MS) technology, comprehensively analyzed the micro ecology, physicochemical factors, and volatile components during pit fermentation, comparing traditional fermentation Zaopei (TZP) and mechanized fermentation Zaopei (MZP). According to the research findings, the dominant microorganisms in the fermentation process of ZP comprise Lactobacillus, Monascus, Issatchenkia, and Zygosaccharomyces. In addition, functional microorganisms like Zygosaccharomyces, Monascus, Issatchenkia, Leiothecium, Candida, Pichia, and others exhibited differences on day 0 and throughout the fermentation process. These differences are attributed to the effects of distinct fermentation environment and physicochemical factors. Furthermore, comprehensive analysis detected 87 volatile compounds in TZP and MZP, with 56 showing significant differences, primarily including alcohols, aldehydes, ketones, acids, esters, and aromatics. Additionally, fermentation can be classified into two phases based on ethanol and volatile compounds production: the initial phase (0–12 days, P1) primarily focuses on alcohols production, while the subsequent phase (12–30 days, P2) concentrates on volatile compounds generation. The subsequent correlation analysis indicates that variations in volatile compounds primarily arise from shifts in microbial composition, with notable differences observed in fungi, specifically Monascus, Zygosaccharomyces, and Issatchenkia, which drive the disparities in volatile compounds. This study provides an important theoretical basis and practical guidance for the realization of mechanized high-quality production of JB.

ETHNIC STUDY OF ADUWA KO JAANR, A LESSER-KNOWN FERMENTED GINGER MILD ALCOHOLIC BEVERAGE OF EASTERN HIMALAYAS

Consumption of fermented foods and beverages is a part of the dietary cultures of the Himalayan community and is prevalent amongst various ethnic groups in this region. Native of the Himalayan range ferment food and beverages using 'ethno-microbiological' knowledge acquired and practiced since ages, which lacks documentation. This knowledge is transmitted through practice and verbally to new generations. Women folk are engaged in this traditional fermentation culture with cultural and ethnic significance. In addition to its distinctive tastes, fermented foods and beverages provide health advantages to indigenous people. It becomes essential to highlight their scientific value due to their health benefits and ethnic relevance. The diverse nature of fermented foods and beverages, the fermentation process, and the traditional knowledge behind fermentation are a heritage of the eastern Himalayas. Traditional fermentation, in which raw materials are organic and natural starter culture is used, is part of the people's socio-economic lifestyle. Their preservation highlights organic and conventional practices as an excellent alternative to a healthy lifestyle. The present study documents a lesser-known mild-alcoholic fermented beverage, 'Aduwa ko Jaanr,' from the Eastern Himalayan region. A steady decline in traditional fermentation practices has recently been observed due to changes in food habits and culinary practices.

Exploring volatile compounds and microbial dynamics: Kluyveromyces marxianus and Hanseniaspora opuntiae reduce Forastero cocoa fermentation time

Traditional cocoa bean fermentation is a spontaneous process and can result in heterogeneous sensory quality. For this reason, yeast-integrated starter cultures may be an option for creating consistent organoleptic profiles. This study proposes the mixture of Hanseniaspora opuntiae and Kluyveromyces marxianus (from non-cocoa fermentation) as starter culture candidates. The microorganisms and volatile compounds were analyzed during the cocoa fermentation process, and the most abundant were correlated with predominant microorganisms. Results showed that Kluyveromyces marxianus, isolated from mezcal fermentation, was identified as the dominant yeast by high-throughput DNA sequencing. A total of 63 volatile compounds identified by HS-SPME-GC–MS were correlated with the more abundant bacteria and yeast using Principal Component Analysis and Agglomerative Hierarchical Clustering. This study demonstrates that yeasts from other fermentative processes can be used as starter cultures in cocoa fermentation and lead to the formation of more aromatic esters, decrease the acetic acid content.

Efficient production of polyhydroxybutyrate using lignocellulosic biomass derived from oil palm trunks by the inhibitor-tolerant strain Burkholderia ambifaria E5-3.

Lignocellulosic biomass is a valuable, renewable substrate for the synthesis of polyhydroxybutyrate (PHB), an ecofriendly biopolymer. In this study, bacterial strain E5-3 was isolated from soil in Japan; it was identified as Burkholderia ambifaria strain E5-3 by 16S rRNA gene sequencing. The strain showed optimal growth at 37°C with an initial pH of 9. It demonstrated diverse metabolic ability, processing a broad range of carbon substrates, including xylose, glucose, sucrose, glycerol, cellobiose, and, notably, palm oil. Palm oil induced the highest cellular growth, with a PHB content of 65% wt. The strain exhibited inherent tolerance to potential fermentation inhibitors derived from lignocellulosic hydrolysate, withstanding 3g/L 5-hydroxymethylfurfural and 1.25g/L acetic acid. Employing a fed-batch fermentation strategy with a combination of glucose, xylose, and cellobiose resulted in PHB production 2.7-times that in traditional batch fermentation. The use of oil palm trunk hydrolysate, without inhibitor pretreatment, in a fed-batch fermentation setup led to significant cell growth with a PHB content of 45% wt, equivalent to 10g/L. The physicochemical attributes of xylose-derived PHB produced by strain E5-3 included a molecular weight of 722kDa, a number-average molecular weight of 191kDa, and a polydispersity index of 3.78. The amorphous structure of this PHB displayed a glass transition temperature of 4.59°C, while its crystalline counterpart had a melting point of 171.03°C. This research highlights the potential of lignocellulosic feedstocks, especially oil palm trunk hydrolysate, for PHB production through fed-batch fermentation by B. ambifaria strain E5-3, which has high inhibitor tolerance.

Synthetic microbial communities: Novel strategies to enhance the quality of traditional fermented foods.

Consumers are attracted to traditional fermented foods due to their unique flavor and nutritional value. However, the traditional fermentation technique can no longer accommodate the requirements of the food industry. Traditional fermented foods produce hazardous compounds, off-odor, and anti-nutritional factors, reducing product stability. The microbial system complexity of traditional fermented foods resulting from the open fermentation process has made it challenging to regulate these problems by modifying microbial behaviors. Synthetic microbial communities (SynComs) have been shown to simplify complex microbial communities and allow for the targeted design of microbial communities, which has been applied in processing traditional fermented foods. Herein, we describe the theoretical information of SynComs, particularly microbial physiological processes and their interactions. This paper discusses current approaches to creating SynComs, including designing, building, testing, and learning, with typical applications and fundamental techniques. Based on various traditional fermented food innovation demands, the potential and application of SynComs in enhancing the quality of traditional fermented foods are highlighted. SynComs showed superior performance in regulating the quality of traditional fermented foods using the interaction of core microorganisms to reduce the hazardous compounds of traditional fermented foods and improve flavor. Additionally, we presented the current status and future perspectives of SynComs for improving the quality of traditional fermented foods.

Effect of fermentation on nutrient composition, antinutrients, and mineral bioaccessibility of finger millet based Injera: A traditional Ethiopian food

Finger millet, like other cereals, contains high amounts of antinutrients that bind minerals, making them unavailable for absorption. This study explores the effect of traditional fermentation on nutritional, antinutritional, and subsequent mineral bioaccessibility (specifically iron, zinc, and calcium) of finger millet based Injera. Samples of fermented dough and Injera prepared from light brown and white finger millet varieties were analyzed for nutritional composition, antinutritional content, and mineral bioaccessibility following standard procedures. With some exceptions, the proximate composition of fermented dough was significantly affected by fermentation time. Compared to unfermented flour, the phytate and condensed tannin content significantly (p < 0.05) decreased for fermented dough and Injera samples. A strong decline in phytate and condensed tannin content was observed in white finger millet Injera as fermentation time increased, compared to light brown finger millet based Injera. The mineral bioaccessibility of Injera prepared from finger millet and maize composite flour increased with fermentation time, leading to a significant increase in bioaccessible iron, zinc, and calcium, ranging from 15.4–40.0 %, 26.8–50.8 %, and 60.9–88.5 %, respectively. The results suggest that traditional fermentation can be an effective method to reduce phytate and condensed tannin content, simultaneously increasing the bioaccessibility of minerals in the preparation of finger millet based Injera.

Introducing Bacillus natto and Propionibacterium shermanii into soymilk fermentation: A promising strategy for quality improvement and bioactive peptide production during in vitro digestion

Herein, the texture properties, polyphenol contents, and in vitro protein digestion characteristics of soymilk single- or co-fermented by non-typical milk fermenter Bacillus natto (B. natto), Propionibacterium freudenreichii subsp. shermanii (P. shermanii), and traditional milk fermenter were evaluated. Co-fermenting procedure containing B. natto or P. shermanii could raise the amounts of gallic acid, caffeic acid, and GABA when compared to the unfermented soymilk. Co-fermented soymilk has higher in vitro protein digestibility and nutritional protein quality. Through peptidomic analysis, the co-work of P. shermanii and Lactobacillus plantarum (L. plantarum) may release the highest relative percentage of bioactive peptides, while the intervention of B. natto and Streptococcus thermophilus (S. thermophilus) resulted in more differentiated peptides. The multi-functional bioactive peptides were mainly released from glycine-rich protein, β-conglycinin alpha subunit 1, and ACB domain-containing protein. These findings indicated the potential usage of B. natto/S. thermophilus or P. shermanii/L. plantarum in bio-enhanced soymilk fermentation.

Selection of a multi-species starter culture for mustard seed fermentation to enhance polyunsaturated fatty acids and improve gastrointestinal health markers

Selection of a multi-species starter culture for mustard seed fermentation to enhance polyunsaturated fatty acids and improve gastrointestinal health markers

A machine learning-based approach for improving plasmid DNA production in Escherichia coli fed-batch fermentations.

Artificial Intelligence (AI) technology is spearheading a new industrial revolution, which provides ample opportunities for the transformational development of traditional fermentation processes. During plasmid fermentation, traditional subjective process control leads to highly unstable plasmid yields. In this study, a multi-parameter correlation analysis was first performed to discover a dynamic metabolic balance among the oxygen uptake rate, temperature, and plasmid yield, whilst revealing the heating rate and timing as the most important optimization factor for balanced cell growth and plasmid production. Then, based on the acquired on-line parameters as well as outputs of kinetic models constructed for describing process dynamics of biomass concentration, plasmid yield, and substrate concentration, a machine learning (ML) model with Random Forest (RF) as the best machine learning algorithm was established to predict the optimal heating strategy. Finally, the highest plasmid yield and specific productivity of 1167.74mg L-1 and 8.87mg L-1/OD600 were achieved with the optimal heating strategy predicted by the RF model in the 50 L bioreactor, respectively, which was 71% and 21% higher than those obtained in the control cultures where a traditional one-step temperature upshift strategy was applied. In addition, this study transformed empirical fermentation process optimization into a more efficient and rational self-optimization method. The methodology employed in this study is equally applicable to predict the regulation of process dynamics for other products, thereby facilitating the potential for furthering the intelligent automation of fermentation processes.