Fermentative Microorganisms Research Articles

Bacterial Cellulose Applications in Electrochemical Energy Storage Devices.

Bacterial cellulose (BC) is produced via the fermentation of various microorganisms. It has an interconnected 3D porous network structure, strong water-locking ability, high mechanical strength, chemical stability, anti-shrinkage properties, renewability, biodegradability, and a low cost. BC-based materials and their derivatives have been utilized to fabricate advanced functional materials for electrochemical energy storage devices and flexible electronics. This review summarizes recent progress in the development of BC-related functional materials for electrochemical energy storage devices. The origin, components, and microstructure of BC are discussed, followed by the advantages of using BC in energy storage applications. Then, BC-related material design strategies in terms of solid electrolytes, binders, and separators, as well as BC-derived carbon nanofibers for electroactive materials are discussed. Finally, a short conclusion and outlook regarding current challenges and future research opportunities related to BC-based advanced functional materials for next-generation energy storage devices suggestions are proposed.

Honeysuckle branches and lactobacillus enhance quality by changing the composition and diversity of microorganisms in alfalfa silage fermentation

The incorporation of honeysuckle as a silage additive in alfalfa production has yielded promising results; however, the underlying microbial mechanisms during fermentation remain poorly understood. This study leveraged high-throughput sequencing and nutrient profiling to elucidate microbial population dynamics over 45 days of anaerobic fermentation within a vacuum-assisted co-culture system comprising varying fresh weight ratios of honeysuckle branches, Lactobacillus, and alfalfa. The experimental design encompassed a Lactobacillus-supplemented treatment (M group) and an unsupplemented control (R group), each with five honeysuckle percentages (5%, 10%, 15%, 20%, 25%) and respective negative controls. Our findings reveal that the combined use of honeysuckle branches and Lactobacillus significantly impacts microbial community composition and diversity during alfalfa silage fermentation. The Mantel test underscores Lactobacillus's absence-dependent correlation of bacterial communities with pH and lactic acid, whereas its presence redirects these correlations towards total nitrogen, NH4+-N, neutral detergent fiber, and crude protein as key bacterial population drivers. Fungal populations exhibited analogous trends. Moreover, the combined additives reshaped microbial populations during anaerobic fermentation, altering interaction networks and intensifying microbial interplay. Notably, Lactobacillus introduction on a honeysuckle branch base diminished fungal core OTUs, thereby mitigating fungal contamination risks. This study also identified biomarkers unique to each treatment condition. Collectively, our research provides a molecular framework for employing honeysuckle branches and Lactobacillus as innovative silage additives in alfalfa production, fostering the development of eco-friendly and hygienic feed and farming industries.

Unraveling the regional environmental ecology dominated baijiu fermentation microbial community succession and associated unique flavor

Chinese baijiu as one of the famous distilled liquor in which fermented in open environments, with various microorganisms (i.e., bacteria, fungi, and yeast) involved in their brewing process, and created corresponding unique flavor. However, the sources of environmentally enriched microbial communities associated with liquor fermentation are still being characterized yet. Given the dependence of microbial growth and reproduction on environmental ecology, it is important to understand the correlation between baijiu fermentation microbial community and surrounding environmental ecology (i.e., temperature, humidity, wind, and precipitation). This study systematically overviewed the sources of microorganisms in the Jiang-flavor-Baijiu fermentation system. The results showed that microorganisms in baijiu brewing (i.e., mold, lactic acid bacteria, and yeast) mainly originated from surrounding environmental matrices, including the air (i.e., Yeast, Streptomyces and Bacillus), soil (i.e., Xanthomonas, Methanococcus and Comamonas) and water (i.e., Flavobacterium, Acinetobacter, and Pseudomonas) via atmospheric transport, raw material transfer and surface runoff. In addition, the unique baijiu fermentation microbial community diversity depends on local geology and meteorological conditions, highlighting that the structural stability and diversity of the microorganisms in the Baijiu brewing process dominated by local environmental ecology. We also explored the regional environmental conditions on the microbial community and found that the unique Jiang-flavor-Baijiu fermentation microbial community diversity depends on local geology and meteorological conditions. The Jiang-flavor-Baijiu workshop is located in the basin of the middle-and low latitude mountainous areas, with sufficient solar irradiation and rainfall, high air humidity, and low wind speed that favor the growth and propagation of Baijiu fermentation microorganisms. Therefore, the obtained conclusions provide new insights unraveling the key factor controlling the unique flavor of Chinese Baijiu, where protecting the ecology of baijiu brewing-regions is fundamental for maintaining the long-term quality of baijiu.

Impacts of Protein and Energy Levels on Rumen Fermentation and Microbial Activity Under Different Incubation Temperatures

This study aimed to explore the effects of different incubation temperatures on ruminal fermentation and rumen microorganisms and determine the appropriate protein and energy levels to enhance microbial protein synthesis using an in vitro system. Rumen inoculum was collected from two fistulated Holstein heifers (trial 1: BW: 652.3 kg ± 25.2; trial 2: BW: 683.3 kg ± 30.2) and assessed using a closed-batch culture system. The experimental model employed a 2 × 5 factorial arrangement using incubation temperatures set to 39 and 41 °C, with protein levels set to 12.0, 13.5, 15.0, 16.5, and 18.0% of DM in trial 1 or with energy levels set to 2.4, 2.5, 2.6, 2.7, and 2.8 Mcal/kg of DM in trial 2. The data were analyzed using the MIXED procedure. The results showed increased (p < 0.05) NH3-N concentrations and total volatile fatty acids (TVFAs) with higher incubation temperatures, while the liquid-associated bacterial (LAB) amounts decreased (p < 0.05) in trials 1 and 2. The interaction between the energy level and incubation temperature affected (p < 0.05) the LAB protein levels in trial 2. Higher protein levels led to increased (p < 0.05) NH3-N and acetate concentrations, but it decreased (p < 0.05) the propionate percentage. Conversely, higher energy levels decreased (p < 0.05) the amount of acetate and increased the propionate concentration, altering the acetate-to-propionate ratio. However, no interaction involving TVFA and LAB was observed between the incubation temperature and the protein or energy levels. Changes in the NH3-N, TVFAs, and LAB protein amounts were observed under different incubation temperatures and energy levels. In conclusion, these findings provide insight into the metabolic adaptation under different ruminal temperatures and the impacts of dietary adjustments on rumen fermentation and microbial activity. However, there are limitations to replicating the complex physiological responses that occur within the whole body solely through in vitro experiments.

Preparation of carboxymethylated curdlan oligosaccharides and application on plant disease control

Curdlan is produced by fermentation of microorganisms, which is an insoluble β-(1 → 3)-D-glucans. To better effectively utilize native curdlan, firstly, a derivative from curdlan, carboxymethylated curdlan (CMCD), with different degrees of substitution (DS) DS ∼ 0.20, DS ∼ 0.43 and DS ∼ 0.82 were prepared in this study. Carboxymethylation increases solubility in water more than native curdlan. Moreover, CMCDs were investigated to be hydrolyzed by CcGluE, an endo-β-1 → 3-glucanase and generated the degradation products were oligosaccharides with degrees of polymerization (DP) mainly ranging from 2 to 7. CcGluE also showed high thermal and pH stability when CMCD ∼ 0.43 was used as a substrate. Then these oligosaccharides generated by different CMCDs were applied to Arabidopsis and the activity in inducing defense responses were detected after being treated by the pathogen of Pseudomonas syringae pv tomato DC3000 (Pst DC3000). CMCD (DS ∼ 0.20) degradation oligosaccharide (CMCD ∼ 0.20 OS) pre-treatment was the just one that significantly enhanced the disease resistance to Pst DC3000, which is mediated by the salicylic acid (SA) signaling pathway in plants. The findings offer new insights into the application of curdlan, demonstrating that carboxymethylation enhances its solubility in water. Additionally, the oligosaccharide products derived from CMCD degradation show promising prospects for controlling plant diseases in agriculture.

Influences and mechanisms of iron input for methane productions in peatlands.

Atmospheric deposition provides a stable iron source for peatlands. The influences of Fe input on methane (CH4) productions and the underlying mechanisms remain unclear. We conducted a microcosm experiment with peat sediments collected from the Qinghai-Tibet Plateau of China to explore the effects of ferrihydrite reductionfor CH4 productions in peatlands by using geochemical analyses including 57Fe Mössbauer spectroscopy and three-dimensional fluorescence spectroscopy (3D-EEM) in combination with high-throughput sequencing of 16S rRNA and real-time fluorescence quantitative PCR (qPCR). Results showed that ferrihydrite reduction significantly increased CH4 production, being 30 times of that under the control. Selective extractions for iron oxides and 57Fe Mössbauer spectroscopy measurements revealed that no crystalline secondary iron minerals were formed during the ferrihydrite reduction process. The addition of ferrihydrite enhanced the degradation of dissolved organic matter (DOM) in peat soil, resulting in a reduction in the concentration of dissolved organic carbon (DOC). Furthermore, the relative abundance of typical fermentative microorganisms in peat sediments, including Acidobacteriota and Bacteroidota, significantly increased. Such a result indicated that reduction of ferrihydrite accelerated organic matter decomposition and increased substrate concentration required for methanogenesis. Furthermore, a co-increase in relative abundance of Geobacter, Geothrix, and Methanobacterium in the ferrihydrite-amended group suggested a potential synergistic interaction that may promote the CH4 production. Our results demonstrated that ferrihydrite reduction could significantly enhance CH4 production and play a vital role in regulating CH4 emissions in peatlands.

PSI-11 Effect of thymol on forage utilization, rumen fermentation, and rumen microorganisms in beef steers

Abstract Essential oils (EOs) have been extensively researched for their ability to modulate rumen microbial populations and, subsequently, rumen fermentation and enteric methane production. However, biological changes from dietary EOs are inconsistent due to the varying presence and concentrations of terpenes, the main bioactive component of EOs. Further, mechanisms by which terpenes exert their actions are not well understood due to structural variety and complexity. Therefore, terpenes should be researched individually and at known dosages. The objective of this study was to determine the effects of thymol on forage utilization and rumen microbial populations in beef steers. Thymol is a terpene from thyme and oregano EOs which is thought to reduce methanogenesis in ruminants. As thymol has potent antimicrobial activity, we aimed to identify a dose that favorably modulates microbial populations without interfering with forage utilization. Accordingly, we utilized beef steers (n = 4) in a 4×4 Latin square design experiment with four 28-d periods. Four doses of thymol [0 (CON), 120, 240, and 480 mg thymol/kg intake] were administered on alfalfa cubes to a basal hay diet which was provided ad libitum. Intake and digestion were determined on d 9 to 12 and rumen contents were collected then separated into liquid and solid fractions on d 14 of each period. DNA was extracted from the liquid and solid rumen contents and analyzed with whole genome shotgun sequencing. Forage organic matter intake, total digestible organic matter intake, and organic matter digestibility were not affected by treatment (P ≥ 0.66). Ruminal ammonia, total volatile fatty acids, and rumen pH were also not affected by treatment (P ≥ 0.30). However, for 240 mg thymol/kg intake, molar proportions of acetate were significantly increased compared with 120 mg thymol/kg intake (P ≤ 0.02) and tended to be greater than for 480 mg thymol/kg intake (P = 0.08). Propionate was significantly decreased (P ≤ 0.02) for 240 mg thymol/kg intake compared with other treatments. Numerous lactic acid bacteria (LAB) including multiple Lactobacillus, Enterococcus, and Pediococcus species were increased for thymol treatments compared with CON. The ammonia producing bacteria Prevotella bryantii was increased at 240 and 480 mg thymol/kg intake compared with 120 mg thymol/kg intake (P ≤ 0.05). Methanogenic microbial species, uncultured Methanobrevibacter sp., and total archaeal abundances were increased in the solid microenvironment versus CON for 240 mg thymol/kg intake (P ≤ 0.04). Ultimately, our data indicate that thymol did not negatively affect forage utilization or fermentation products, although microbial populations were affected. While methanogenic archaea were not reduced with thymol supplementation, the increases in LAB may indicate an alternative mechanism for thymol to modulate microbial populations and methanogenesis. These data provide insight into the impact of specific doses of thymol on cattle and provide a foundation for future research that specifically studies the mechanisms by which terpenes and EOs exert biological actions.

Biohydrogen Produced via Dark Fermentation: A Review

Hydrogen (H2) is a highly efficient and clean energy source with the potential for renewable energy. The production of H2 from biological routes such as biophotolysis, photofermentation, dark fermentation, and bioelectrochemical production is characterized as a renewable alternative to current production, which is mainly based on energy-intensive electrochemical and thermochemical processes and responsible for the emission of high amounts of environmentally harmful compounds. Dark fermentation is the most efficient and cost-effective method for producing biohydrogen, making it a key research focus. This article offers a comprehensive overview of the dark fermentation process with the aim of enhancing hydrogen productivity and yields. Aspects related to the main substrates used, the inoculum sources and their pretreatment, and physical-chemical parameters of the process are covered. Furthermore, this manuscript addresses topics such as process integration, genetic and metabolic engineering of fermentative microorganisms, and the main types of bioreactors aimed at greater yields and productivity of biohydrogen to enable its production through dark fermentation on a larger scale.

Unveiling the relationship of volatile compounds and microbial communities in light-struck taste rice wine: A comprehensive analysis

Light-struck taste rice wine (LST-RW) is the most popular new rice wine at present, which is brewed by a variety of microorganisms. However, the relationship between microorganisms and flavor substances in light-struck taste rice wine is still unexplored. In this study, high-throughput sequencing, high-performance liquid chromatography (HPLC), headspace solid-phase microextraction (HS-SPME), and gas chromatography–mass spectrometry (GC–MS) were used to prove that microbial community had significant influence on flavor substances during light-struck taste rice wine fermentation. The results indicated a consistent increase in the majority of amino acids and organic acids within LST-RW with extended fermentation duration. A total of 49 volatile flavor compounds, including alcohols, esters, and aldehydes, were identified. In the brewing process of LST-RW, Bacillus (17.13 %) and Saccharopolyspora (15.55 %) emerge as the predominant bacterial genera; Aspergillus (83.34 %) and Saccharomyces (15.21 %) emerged as the dominant fungal genera. A notable correlation was observed between fermentation microorganisms and flavor substances. Microorganism species exhibiting strong co-exclusion or symbiotic relationships were also identified. The research findings offer a theoretical reference for optimizing and innovating the fermentation process of LST-RW.

Analysis of Phenolic Content of Green Tea Kombucha and Butterfly Pea (Clitoria Ternatea L.) Flower Kombucha Using Spectrophotometer Uv-Vis

Kombucha is a health drink that comes from fermented green tea and microorganisms such as Acetobacter xylinum. Kombucha is believed to have high antioxidant content. Butterfly pea flowers (Clitoria ternatea L.) can be used as a basic ingredient for making kombucha because they are believed to have high phenolic content. Phenolics are compounds that have hydroxyl groups (-OH) and contribute most to antioxidant activity. The aim of this research was to determine the levels of phenolic compounds in green tea kombucha and butterfly pea flower kombucha. This research used experimental research by testing phenolic levels using a spectrophotometer uv-vis instrument. The results showed that the phenolic content of green tea kombucha was 162.35 mg/L GAE and butterfly pea flower kombucha was 124.46 mg/L GAE. Thus, the highest phenolic content is found in green tea kombucha.

Exploring the Microbial Diversity of Botswana’s Traditional Sourdoughs

Sourdough is one of the oldest technologies employed by humans to leaven bread because of its ability to enhance the flavour and structure of bread using micro-organisms. However, there is a lack of comprehensive information in Botswana regarding the diversity of sourdough starters and the fermentative micro-organisms responsible for spontaneous fermentation. The present study aimed to explore the microbial species diversity of sourdoughs in Botswana and gain insight into the unique microbial communities involved in sourdough production. A total of nine samples were collected from different areas in Botswana. The microbial diversity in sourdoughs was characterized through the sequencing of amplicons of the 16S ribosomal DNA and internal transcribed spacer regions. In silico polymerase chain reaction–restriction fragment length polymorphism and phylogenetics were utilized to determine the genetic diversity among the isolates. The dominant yeast species identified were Saccharomyces cerevisiae, Wickerhamomyces anomamlus, Pichia kudriazverii and kazachstania humilis. Additionally, the presence of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, Liquorilactobacillus nageli and Bacillus cereus was also detected. It is worth noting that two species of acetic acid bacteria (AAB), namely Acetobacter pasteurianus and A. indonesiensis, were isolated, though in low levels, but the finding is significant in sourdough fermentation. The low occurrence of AAB (acetic acid bacteria) species observed in this study could be an important finding, as these bacteria are considered understudied, yet they are known to contribute significantly to the final product.

The Probiotic Enterococcus Lactis SF68 as a Potential Food Fermentation Microorganism for Safe Food Production.

Due to the reports describing virulent and multidrug resistant enterococci, their use has become a topic of controversy despite most of them being safe and commonly used in traditionally fermented foods worldwide. We have characterized Enterococcus lactis SF68, a probiotic strain approved by the European Food Safety Authority (EFSA) for use in food and feed, and find that it has a remarkable potential in food fermentations. Genome analysis revealed the potential of SF68 to metabolize a multitude of carbohydrates, including lactose and sucrose, which was substantiated experimentally. Bacteriocin biosynthesis clusters were identified and SF68 was found to display a strong inhibitory effect against Listeria monocytogenes. Fermentation-wise, E. lactis SF68 was remarkably like Lactococcus lactis and displayed a clear mixed-acid shift on slowly fermented sugars. SF68 could produce the butter aroma compounds, acetoin and diacetyl, the production of which was enhanced under aerated conditions in a strain deficient in lactate dehydrogenase activity. Overall, E. lactis SF68 was found to be versatile, with a broad carbohydrate utilization capacity, a capacity for producing bacteriocins, and an ability to grow at elevated temperatures. This is key to eliminating pathogenic and spoilage microorganisms that are frequently associated with fermented foods.

Development of a Robust Saccharomyces cerevisiae Strain for Efficient Co-Fermentation of Mixed Sugars and Enhanced Inhibitor Tolerance through Protoplast Fusion.

The economical and efficient commercial production of second-generation bioethanol requires fermentation microorganisms capable of entirely and rapidly utilizing all sugars in lignocellulosic hydrolysates. In this study, we developed a recombinant Saccharomyces cerevisiae strain, BLH510, through protoplast fusion and metabolic engineering to enhance its ability to co-ferment glucose, xylose, cellobiose, and xylooligosaccharides while tolerating various inhibitors commonly found in lignocellulosic hydrolysates. The parental strains, LF1 and BLN26, were selected for their superior glucose/xylose co-fermentation capabilities and inhibitor tolerance, respectively. The fusion strain BLH510 demonstrated efficient utilization of mixed sugars and high ethanol yield under oxygen-limited conditions. Under low inoculum conditions, strain BLH510 could completely consume all four kinds of sugars in the medium within 84 h. The fermentation produced 33.96 g/L ethanol, achieving 84.3% of the theoretical ethanol yield. Despite the challenging presence of mixed inhibitors, BLH510 successfully metabolized all four sugars above after 120 h of fermentation, producing approximately 30 g/L ethanol and reaching 83% of the theoretical yield. Also, strain BLH510 exhibited increased intracellular trehalose content, particularly under conditions with mixed inhibitors, where the intracellular trehalose reached 239.3 mg/g yeast biomass. This elevated trehalose content contributes to the enhanced stress tolerance of BLH510. The study also optimized conditions for protoplast preparation and fusion, balancing high preparation efficiency and satisfactory regeneration efficiency. The results indicate that BLH510 is a promising candidate for industrial second-generation bioethanol production from lignocellulosic biomass, offering improved performance under challenging fermentation conditions. Our work demonstrates the potential of combining protoplast fusion and metabolic engineering to develop superior S. cerevisiae strains for lignocellulosic bioethanol production. This approach can also be extended to develop robust microbial platforms for producing a wide array of lignocellulosic biomass-based biochemicals.

Hydrolytic Response of Beta-Amylase to Selected Starches when Adsorptively Immobilized on Agarose Gel

Fermentative microorganisms bring about transformative processes in food, thereby enhancing flavor and appearance indices, inhibiting undesirable components, improving shelf and storage life, as well as improving health and nutritional quality parameters. Traditional methods for identification of fermentative microorganisms involve cultivating and analyzing phenotypic characteristics, which are labor-intensive and time-consuming. Advanced molecular techniques such as polymerase chain reaction, whole gene sequencing, next generation sequencing, fluorescent in situ hybridization (FISH), Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), fourier transform infrared spectroscopy and hyper-spectral imaging offer rapid, cost-effective, and reliable identification of bacteria and fungi cultured on agar plates or in liquid media. Techniques, such as genotyping, examine the DNA sequence to determine the genetic makeup of microorganisms, alongside the grouping of isolates via application of phylogenetic tree similarity indices. Overall, modern molecular techniques have revolutionized the identification of fermentative microorganisms, providing efficient and more elaborate alternatives to traditional methods. In this review work, an attempt is made to examine the historical and analytical trends from the conventional methods to the most recent modern tools for effective identification of industrially-important fermentative microorganisms.

Recent Advances in the Identification and Characterization of Fermentative Microorganisms: An Exploratory Review

Fermentative microorganisms bring about transformative processes in food, thereby enhancing flavor and appearance indices, inhibiting undesirable components, improving shelf and storage life, as well as improving health and nutritional quality parameters. Traditional methods for identification of fermentative microorganisms involve cultivating and analyzing phenotypic characteristics, which are labor-intensive and time-consuming. Advanced molecular techniques such as polymerase chain reaction, whole gene sequencing, next generation sequencing, fluorescent in situ hybridization (FISH), Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), fourier transform infrared spectroscopy and hyper-spectral imaging offer rapid, cost-effective, and reliable identification of bacteria and fungi cultured on agar plates or in liquid media. Techniques, such as genotyping, examine the DNA sequence to determine the genetic makeup of microorganisms, alongside the grouping of isolates via application of phylogenetic tree similarity indices. Overall, modern molecular techniques have revolutionized the identification of fermentative microorganisms, providing efficient and more elaborate alternatives to traditional methods. In this review work, an attempt is made to examine the historical and analytical trends from the conventional methods to the most recent modern tools for effective identification of industrially-important fermentative microorganisms.

Mechanistic insights into rumen function promotion through yeast culture (Saccharomyces cerevisiae) metabolites using in vitro and in vivo models.

Yeast culture (YC) enhances ruminant performance, but its functional mechanism remains unclear because of the complex composition of YC and the uncertain substances affecting rumen fermentation. The objective of this study was to determine the composition of effective metabolites in YC by exploring its effects on rumen fermentation in vitro, growth and slaughter performance, serum index, rumen fermentation parameters, rumen microorganisms, and metabolites in lambs. In Trial 1, various YCs were successfully produced, providing raw materials for identifying effective metabolites. The experiment was divided into 5 treatment groups with 5 replicates in each group: the control group (basal diet without additives) and YC groups were supplemented with 0.625‰ of four different yeast cultures, respectively (groups A, B, C, and D). Rumen fermentation parameters were determined at 3, 6, 12, and 24 h in vitro. A univariate regression model multiple factor associative effects index (MFAEI; y) was established to correlate the most influential factors on in vitro rumen fermentation with YC metabolites (x). This identified the metabolites promoting rumen fermentation and optimal YC substance levels. In Trial 2, metabolites in YC not positively correlated with MFAEI were excluded, and effective substances were combined with pure chemicals (M group). This experiment validated the effectiveness of YC metabolites in lamb production based on their impact on growth, slaughter performance, serum indices, rumen parameters, microorganisms, and metabolites. Thirty cross-generation rams (Small tail Han-yang ♀ × Australian white sheep ♂) with good body condition and similar body weight were divided into three treatment groups with 10 replicates in each group: control group, YC group, pure chemicals combination group (M group). Growth performance and serum index were measured on days 30 and 60, and slaughter performance, rumen fermentation parameters, microorganisms, and metabolites were measured on day 60. The M group significantly increased the dressing percentage, and significantly decreased the GR values of lambs (p < 0.05). The concentration of growth hormone (GH), Cortisol, insulin (INS), and rumen VFA in the M group significantly increased (p < 0.05). These experiments confirmed that YC or its screened effective metabolites positively impact lamb slaughter performance, rumen fermentation, and microbial metabolism.

Biochemical and Biorefinery Platform for Second-Generation Bioethanol: Fermentative Strategies and Microorganisms

Bioethanol is the most commonly used biofuel. It is an alternative to replace fossil fuels in renewable energy; it can be produced from lignocellulosic feedstock using a biotechnological process. Their participation of microorganisms is crucial in the bioconversion process of fermentation for ethanol production and can involve bacteria, fungi, and yeasts. However, when working within bioethanol processes from lignocellulose feedstock, microorganisms face some challenges, such as high temperature, high solids content, and the ability to ferment sugars for high ethanol concentration. Such challenges will depend on operative strategies, such as simultaneous saccharification and fermentation, separate hydrolysis and fermentation, semi-simultaneous saccharification and fermentation, and consolidated bioprocessing; these are the most common configurations. This review presents different trends of the microbial role, biochemical application, and fermentation operative strategies for bioethanol production of the second generation.

DIVERSITYOF LACTICACID BACTERIAINVOLVEDIN THE FERMENTATION OF THE TAMARIND FRUIT (TAMARINDUS INDICA) COTE DIVOIRE

In Cote dIvoire, tamarind fruits, from trees growing in the northern part of the country, are used for various food purposes (seasoning dishes, producing acidic beverages, etc.), typically after a fermentation process. These fermented fruits could therefore represent a source of beneficial fermentative microorganisms for the development of starters in biotechnology. A study was therefore undertaken to determine the diversity of lactic acid bacteria involved in tamarind fermentation. For this purpose, a total of 400 tamarind samples were collected from various markets in the cities of Korhogo and Abidjan. Lactic acid bacteria from these samples were screened and counted on MRS agar, and then subjected to identification. A total of 664 strains were isolated, of which 430 isolates were retained. Genus characterization was performed by 16S rRNA gene PCR. For species determination of the isolates, MALDI-TOF proteomics was applied. The results obtained showed that the lactic acid bacteria isolated from tamarind belong to the genera Pediococcus, Lactobacillus, Lacococcus, and Weissella, with a dominance of the genus Lactobacillus (63%) compared to the total number of identified strains, followed by the genus Pediococcus (16%) and finally the genera Weissella (12%) and Lactococcus (8%). The genus Lactobacillus was represented by Lactobacillus plantarum (36%), Lactobacillus fermentum (20.5%), Lactobacillus acidophilus (20%), and Lactobacillus rhamnosus (23.5%). The genus Pediococcuswas represented by Pediococcusacidilactici, the Lactococcus strains were solely composed of Lactococcus lactis. As for the genus Weissella, only Weissella sp. was involved in tamarind fermentation.

Bacillus licheniformis-based intensive fermentation of Tibetan tea improved its bioactive compounds and reinforced the intestinal barrier in mice.

Tibetan tea changes during microorganism fermentation. Research on microorganisms in Tibetan tea has focused on their identification, while studies on the influence of specific microorganisms on the components and health functions of Tibetan tea are lacking. Bacillus licheniformis was inoculated into Tibetan tea for intensive fermentation, and the components of B. licheniformis-fermented tea (BLT) were detected by liquid chromatography with tandem mass spectrometry (UHPLC-TOF-MS), and then the effects of BLT on intestinal probiotic functions were investigated by experiments on mice. The results revealed the metabolites of BLT include polyphenols, alkaloids, terpenoids, amino acids, and lipids. Intensified fermentation also improved the antioxidant capacity in vivo and the protective effect on the intestinal barrier of Tibetan tea. In addition, the enhanced fermentation of Tibetan tea exerted intestinal probiotic effects by modulating the relative abundance of short-chain fatty acid-producing bacteria in the intestinal flora. Therefore, intensive fermentation with B. licheniformis can improve the health benefits of Tibetan tea.

Removal of phenolic inhibitor compounds from hydrolysates and post-fermentation broths by using a hydrophobic magnetic deep eutectic solvent

Hydroxymethylfurfural (HMF), furfural (FF), hydroquinone (HQ), and vanillin (VAN) are among the main inhibitors generated during most of biomass pre-treatments prior to fermentation processes. They are recognized as toxic to several fermentative microorganisms and therefore cause a decrease in biohydrogen or biofuel production (after hydrolysis). Moreover, if they are released into aqueous solutions (after fermentation), they can be detrimental to the ecosystem. In this research, a new method for removing these inhibitor compounds from the broth after hydrolysis and fermentation is proposed. A hydrophobic magnetic deep eutectic solvent (HMDES), based on menthol: nonanoic acid in a mole ratio of 2:1 was prepared and magnetized with Fe3O4 nanoparticles and applied for effective sorption and removal of these inhibitors from the broth after fermentation and for biomass hydrolysates. Parameters affecting sorption, such as pH, volume of the inhibitors, initial concentration of inhibitors, volume of HMDES, temperature, stirring speed, and contact time, were studied and optimized. Under optimum conditions, the removal efficiency for HQ, HMF, FF, and VAN was obtained as 92.97, 86.72, 82.86 and 95.12% for the model samples. In addition, the removal efficiency of real samples after hydrolysis and fermentation for HQ, HMF, FF and VAN were higher than 83.3, 71.42, 69.99 and 76.80%, respectively. The studies on HMDES regeneration revealed that the removal efficiency remained constant even after undergoing 13 cycles of regeneration. The mechanism of inhibitor removal suggests that hydrogen bonding or van der Waals interactions may serve as the predominant factor influencing the extraction process.