Fermentative Bacteria Research Articles

Microbial aromatic amino acid metabolism is modifiable in fermented food matrices to promote bioactivity

Ingestion of fermented foods impacts human immune function, yet the bioactive food components underlying these effects are not understood. Here, we interrogated whether fermented food bioactivity relates to microbial metabolites derived from aromatic amino acids, termed aryl-lactates. Using targeted metabolomics, we established the presence of aryl-lactates in commercially available fermented foods. After pinpointing fermented food-associated lactic acid bacteria that produce high levels of aryl-lactates, we identified fermentation conditions to increase aryl-lactate production in food matrices up to 5 × 103 fold vs. standard fermentation conditions. Using ex vivo reporter assays, we found that food matrix conditions optimized for aryl-lactate production exhibited enhanced agonist activity for the human aryl-hydrocarbon receptor (AhR) as compared to standard fermentation conditions and commercial products. Reduced microbial-induced AhR activity has emerged as a hallmark of many chronic inflammatory diseases, thus we envision strategies to enhance AhR bioactivity of fermented foods to be leveraged to improve human health.

Enhancing iron biogeochemical cycling for canga ecosystem restoration: insights from microbial stimuli.

The microbial-induced restoration of ferruginous crusts (canga), which partially cover iron deposits and host unique ecosystems, is a promising alternative for reducing the environmental impacts of the iron mining industry. To investigate the potential of microbial action to accelerate the reduction and oxidation of iron in substrates rich in hematite and goethite, four different microbial treatments (water only as a control - W; culture medium only - MO; medium + microbial consortium - MI; medium + microbial consortium + soluble iron - MIC) were periodically applied to induce iron dissolution and subsequent precipitation. Except for W, all the treatments resulted in the formation of biocemented blocks. MO and MI treatments resulted in significant goethite dissolution, followed by precipitation of iron oxyhydroxides and an iron sulfate phase, due to iron oxidation, in addition to the preservation of microfossils. In the MIC treatment, biofilms were identified, but with few mineralogical changes in the iron-rich particles, indicating less iron cycling compared to the MO or MI treatment. Regarding microbial diversity, iron-reducing families, such as Enterobacteriaceae, were found in all microbially treated substrates. However, the presence of Bacillaceae indicates the importance of fermentative bacteria in accelerating the dissolution of iron minerals. The acceleration of iron cycling was also promoted by microorganisms that couple nitrate reduction with Fe(II) oxidation. These findings demonstrate a sustainable and streamlined opportunity for restoration in mining areas.

Lactic acid bacteria fermentation improves physicochemical properties, bioactivity, and metabolic profiles of Opuntia ficus-indica fruit juice

Lactic acid bacteria (LAB) fermentation has been proven to promote human health. The effect of different LAB fermentation on the quality of Opuntia ficus-indica fruit juice (OFIJ) was investigated. OFIJ was an excellent substrate for fermentation, with colony counts of more than 8 log CFU/mL after fermentation. The fermentation altered the acid and sugar contents. Simultaneously, the total phenolic and anthocyanin contents significantly increased. Antioxidant activity enhanced significantly in Lactiplantibacillus plantarum HNU082-fermented OFIJ, primarily in ABTS+ (increased by 16.81%) and DPPH (increased by 23.62%) free radical scavenging ability. Lacticaseibacillus paracasei HNU502-fermented OFIJ showed the most potent inhibition of xanthine oxidase (IC50 = 31.01 ± 3.88 mg TAC/L). Analysis of volatile and non-volatile compounds indicated that fermentation changed the flavor quality and metabolic profiles and caused the most significant modifications in amino acid metabolism. These findings offer valuable information into processing of OFIJ, making it a great choice for functional foods.

Co-occurrence network and functional profiling of the bacterial community in the industrial pile fermentation of Qingzhuan tea: Understanding core functional bacteria

The distinct quality of Qingzhuan tea is greatly influenced by the bacterial community but was poorly characterized. Therefore, this study investigated the Co-occurrence network and functional profiling of the bacterial community, with special attention paid to core functional bacteria in the industrial pile fermentation. Microbiomics analysis indicated that Klebsiella and Pantoea dominated raw tea leaves, and were rapidly replaced by Pseudomonas in pile fermentation, but substituted mainly by Burkholderia and Saccharopolyspora in final fermented tea. Bacterial taxa were grouped into 7 modules with the dominant in module I, III, and IV, which were involved in flavor formation and biocontrol production. Functional profiling revealed that “penicillin and cephalosporin biosynthesis” increased in pile fermentation. Twelve bacterial genera were identified as core functional bacteria, in which Klebsiella, Pantoea, and Pseudomonas also dominated the pile fermentation. This work would provide theoretical basis for its chemical biofortification and quality improvement by controlling bacterial communities.

Preparation and characterization of grouper bone peptides-calcium complex by lactic acid bacteria fermentation

In this study, grouper bone peptides-calcium complex (GPs-Ca) was prepared by lactic acid bacteria fermentation, and its structure and stability were analyzed. Response surface methodology (RSM) optimization was used to determine the optimal fermentation conditions as follows: 4% (v/v) inoculum size, 4.5 g/100 mL glucose addition and fermentation time 75 h,under which the soluble calcium content was 5953.61 mg/L and the peptide content was 21.75 mg/mL. The results of ultraviolet–visible absorption spectroscopy (UV) and fluorescence spectroscopy (Fs) showed a significant spectral shift for GPs-Ca relative to grouper bone peptides (GPs), indicating that peptide combined with calcium to produce a new substance after fermentation. Fourier transform infrared spectroscopy (FTIR) showed that carboxyl groups participated in the formation of GPs-Ca. Scanning electron microscopy (SEM) showed that calcium ions were embedded or adsorbed on the peptide surface. According to the stability analysis, GPs-Ca was stable during heating, alkaline environment and intestinal digestion, but easily dissociated in acidic environment. GPs-Ca prepared by lactic acid bacteria fermentation has the potential to be used as a new type of calcium supplement product, which provides a scientific basis for the high-value utilization of grouper bone.

Addition of lactic acid bacteria modulates microbial community and promotes the flavor profiles of Kombucha

This study explores the impact of innovative food processing on food-derived bioactive components through integrating lactic acid bacteria (LAB) in kombucha fermentation. The study showcased how this technique, involving four LAB strains, drastically transformed the beverage's chemical composition, favoring its flavor properties and microbial diversity. LAB integration significantly lessened total and acetic acid content, enhancing kombucha's flavor, especially with the effective strain Lactiplantibacillus plantarum. LAB's presence fostered the production of alcohols and esters further enhancing the kombucha's flavor. Post-72-h quality shifts detected through Principal Component Analysis were potentially attributed to the LAB's role in generating volatile compounds. High-throughput sequencing denoted Zygosaccharomyces, Pichia, Komagataeibacter, and Gluconacetobacter as leading microbial genera, with Pichia correlating strongly with flavor compounds. The study also unveiled six key volatile compounds and their metabolic pathways. Thus, this pilot investigation presents essential insights for future strategies to enhance kombucha flavor, also shedding light on the health-promoting foods sector.

Insights into the effect of nitrate photolysis on short-chain fatty acids production from waste activated sludge in anaerobic fermentation system: Performance and mechanisms

Nitrate photolysis has become an efficient, low-cost and promising technology for emerging contaminants removal, while its performance and mechanism for waste activated sludge (WAS) treatment is still unknown. This study innovatively introduced nitrate photolysis for WAS disintegration, and investigated the effect of nitrate addition (150–375 mg N/L) for short-chain fatty acids (SCFAs) production during anaerobic fermentation (AF). The results showed that nitrate photolysis significantly promoted the SCFAs production from WAS, and peaked at 280.7 mg/g VSS with 7-d fermentation with 150 mg N/L addition (150N-UV), which increased by 8.8–35.0 % and 10.7–23.3 % compared with other photolysis groups and sole nitrate groups. Effective release of the soluble organics was observed in the nitrate photolysis groups during AF, especially soluble proteins, reaching 1505.4 mg COD/L at 9 d in 150N-UV group, promoted by 7.0∼15.7 % than nitrate/nitrate photolysis groups. The model compounds simulation experiment further demonstrated the positive effect of nitrate photolysis on organics hydrolysis and SCFAs accumulation. The result of the radical capture and quenching verified the reactive oxygen species contributed more compared with reactive nitrogen species. Functional group analysis confirmed the effective bioconversion of the macromolecular organics during the fermentation. Moreover, the nitrate photolysis enhanced the enrichment of the functional consortia, including anaerobic fermentation bacteria (AFB), e.g., Fnoticella, Romboutsia, Gracilibacter and Sedimentibacter, and nitrate reducing bacteria (NRB), e.g., Acinerobacter and Ahniella. The macrogenetic analysis further revealed that glycolysis, amino acid metabolism, acetate metabolism and nitrogen metabolism were the dominating metabolic pathways during fermentation, and the abundance of the relevant genes were enhanced in 150N-UV group.

Efficient phosphate and hydrogen recovery from sludge fermentation liquid by sacrificial iron anode in electro-fermentation system

Electro-fermentation (EF) has been extensively studied for recovering hydrogen and phosphorus from waste activated sludge (WAS), while was limited for the further application due to the low hydrogen yield and phosphorus recovery efficiency. This study proposed an efficient strategy for hydrogen and vivianite recovery from the simulated sludge fermentation liquid by sacrificial iron anode in EF. The optimum hydrogen productivity and the utilization efficiency of short chain fatty acids (SCFAs) reached 45.2 mmol/g COD and 77.6% at 5 d in pH 8. Phosphate removal efficiency achieved at 90.8% at 2 d and the high crystallinity and weight percentage of vivianite (84.8%) was obtained. The functional microbes, i.e., anaerobic fermentative bacteria, electrochemical active bacteria, homo-acetogens and iron-reducing bacteria were highly enriched and the inherent interaction between the microbial consortia and environmental variables was thoroughly explored. This work may provide a theoretical basis for energy/resource recovery from WAS in the further implementation.

Improvement of physicochemical properties and quercetin delivery ability of fermentation-induced soy protein isolate emulsion gel processed by ultrasound

This study aimed to investigate the effects of ultrasonic treatment at different powers on the physicochemical properties, microstructure and quercetin delivery capacity of fermentation-induced soy protein isolate emulsion gel (FSEG). The FSEG was prepared by subjecting soy protein isolate (SPI) emulsion to ultrasonic treatment at various powers (0, 100, 200, 300, and 400 W), followed by lactic acid bacteria fermentation. Compared with the control group (0 W), the FSEG treated with ultrasound had higher hardness, water holding capacity (WHC) and rheological parameters. Particularly, at an ultrasonic power of 300 W, the FSEG had the highest hardness (101.69 ± 4.67 g) and WHC (75.20 ± 1.07%) (p < 0.05). Analysis of frequency sweep and strain scanning revealed that the storage modulus (G') and yield strains of FSEG increased after 300 W ultrasonic treatment. Additionally, the recovery rate after creep recovery test significantly increased from 18.70 ± 0.49% (0 W) to 58.05 ± 0.54% (300 W) (p < 0.05). Ultrasound treatment also resulted in an increased β-sheet content and the formation of a more compact micro-network structure. This led to a more uniform distribution of oil droplets and reduced mobility of water within the gel. Moreover, ultrasonic treatment significantly enhanced the encapsulation efficiency of quercetin in FSEG from 81.25 ± 0.62 % (0 W) to 90.04 ± 1.54% (300 W). The bioaccessibility of quercetin also increased significantly from 28.90 ± 0.40% (0 W) to 42.58 ± 1.60% (300 W) (p < 0.05). This study enriches the induction method of soy protein emulsion gels and provides some references for the preparation of fermented emulsion gels loaded with active substances.

A study revealing mechanisms behind the stone cell of Yali pear degradation by mixed‐culture fermentation of lactic acid bacteria and yeast

AbstractThe presence of stone cells in pears is recognized as a problem for the pear processing industry. Bacillus and mold can degrade stone cells because of their potential to digest cellulose and lignin, but they cannot be used for the degradation test of pear stone cells. In this study Lactoplantibacillus plantarum JYLP‐326 was used in single culture or in the mixed culture with Saccharomyces cerevisiae Y2 to study their potential to degrade stone cells during fermentation and the mechanism of degradation was further explored. Synergy in cellulase activity was observed in the mixed‐culture where the maximum activity was observed at 96th hour of fermentation. Activities of endoglucanase, exoglucanase and β‐glucosidase were 1.75, 4.58, and 2.31. The degradation rate of stone cells in the mixed‐culture was 37.67%, which was significantly higher than that the results obtained for single cultures. The results of scanning electron microscopy (SEM) showed that the surface of the cultured stone cells became rough. Metabolomics studies confirmed the presence of specific metabolites related to the degradation of stone cells after the fermentation. It was concluded that the mixed‐culture fermentation using the above‐mentioned strains could be exploited by the pear processing industry to degrade stone cells.

Optimal conditions for nano-emulsified vegetable oil synthesis for the biostimulation of 1,1,2-trichloroethane and vinyl chloride contaminated groundwater in bioreactors

Contamination of groundwater with chlorinated aliphatic hydrocarbons (CAHs) has become increasingly widespread. Enhanced reductive dechlorination (ERD) by emulsified vegetable oil (EVO) is an environmentally friendly, low-carbon and sustainable technology that effectively eliminates the threat from CAHs. To improve the permeability and bioavailability of EVO in the low-permeability substratum, nano-emulsified vegetable oil (nanoEVO) can be synthesized using a modified phase inversion composition method (MPIC) by increasing the emulsification temperature that reduces the shear force required for the formation of nanodroplets and the interfacial tension between the mixed phase and water. The emulsification temperature of 60 °C, the water content of 40–70%, the droplet diameter (DD) of nanoEVO prepared by MPIC is ∼200 nm, and had good monodispersion (≤0.2). The high molecular weight and low solubility of vegetable oil, and similar size of droplet make nanoEVO remains homogeneous after storage for > one year. NanoEVO can effectively biostimulate indigenous bacteria in CAHs-contaminated groundwater to dechlorinate 1,1,2-trichloroethane (1,1,2-TCA) to ethene via vinyl chloride (VC). The maximum dihaloelimination rate of 1,1,2-TCA was ∼66.06 μM·Cl−·day−1 and the maximum hydrogenolysis rate of VC was ∼35.67 μM·Cl−·day−1. NanoEVO effectively increased the relative abundance of Dehalococcoides from <0.10 to 9.61%. The abundances of Dhc 16S rRNA gene and dehalogenase gene vcrA increased by 102 and 103, respectively. Biostimulation shaped the structure of microbial communities and promoted hydrolytic acidification and anaerobic fermentation. Moreover, the syntrophic VFA-oxidizing bacteria participated in secondary fermentation and were closely correlated with H2 consumption metabolism. By providing carbon sources and maintaining an anaerobic environment with stable pH and ORP, nanoEVO biostimulated the hydrolytic acidification led by fermentative bacteria, secondary fermentation with syntrophic VFA-oxidizing bacteria and reductive dechlorination carried out by dechlorinator, thus greatly increasing the CAH-dechlorinating ability of indigenous microbial communities.

Novel 3D printed polysaccharide-based materials with prebiotic activity for potential treatment of diaper rash

Diaper rash, mainly occurring as erythema and itching in the diaper area, causes considerable distress to infants and toddlers. Increasing evidence suggests that an unequal distribution of microorganisms on the skin contributes to the development of diaper dermatitis. Probiotic bacteria, like Staphylococcus epidermidis, are crucial for maintaining a healthy balance in the skin's microbiome, among others, through their fermentative metabolites, such as short-chain fatty acids. Using a defined prebiotic as a carbon source (e.g., as part of the diaper formulation) can selectively trigger the fermentation of probiotic bacteria. A proper material choice can reduce diaper rash incidence by diminishing the skin exposure to wetness and faeces. Using 3D printing, we fabricated carbon-rich materials for the top sheet layer of baby diapers that enhance the probiotic activity of S. epidermidis. The developed materials' printability, chemical composition, swelling ability, and degradation rate were analysed. In addition, microbiological tests evaluated their potential as a source of in situ short-chain fatty acid production. Finally, biocompatibility testing with skin cells evaluated their safety for potential use as part of diapers. The results demonstrate a cost-effective approach for producing novel materials that can tailor the ecological balance of the skin microflora and help treat diaper rash.

Sulfate-reducing bacteria decreases fractional pressure of H2 to accelerate short-chain fatty acids production from waste activated sludge fermentation assisted with zero-valent iron activated sulfite pretreatment

The production of short-chain fatty acids (SCFAs) is constrained by substrate availability and the increased fractional pressure of H2 emitted by acidogenic/fermentative bacteria during anaerobic fermentation of waste activated sludge (WAS). This study introduced a novel approach employing zero-valent iron (ZVI)-activated sulfite pretreatment combined with H2-consuming sulfate-reducing bacteria (SRB) mediation to improve SCFAs, especially acetate production from WAS fermentation. Experimental results showed that the combined ZVI-activated sulfite and incomplete-oxidative SRB (io-SRB) process achieved a peak SCFAs production of 868.11 mg COD/L, with acetate accounting for 80.55 %, which was 7.90- and 2.18-fold higher than that obtained from raw WAS fermentation, respectively. This could be firstly attributed to the SO4− and OH generated by ZVI-activated sulfite, which significantly promoted WAS decomposition, e.g., soluble proteins and carbohydrates increased 14.3- and 10.8-fold, respectively, over those in raw WAS. The biodegradation of dissolved organic matter was subsequently enhanced by the synergistic interaction and H2 transfer between anaerobic fermentation bacteria (AFB) and io-SRB. The positive and negative correlations among AFB, nitrate-reducing bacteria (NRB) and the io-SRB consortia were revealed by molecular ecological network (MEN) and Mantel test. Moreover, the expression of functional genes was also improved, for instance, in relation to acetate formation, the relative abundances of phosphate acetyltransferase and acetate kinase was 0.002 % and 0.005 % higher than that in the control test, respectively. These findings emphasized the importance of sulfate radicals-based oxidation pretreatment and the collaborative relationships of multifunctional microbes on the value-added chemicals and energy recovery from sludge fermentation.

Bioelectrochemical anaerobic digestion mitigates microplastic pollution and promotes methane recovery of wastewater treatment in biofilm system

Bioelectrochemical systems (BES) offer significant potential for treating refractory waste and recovering bioenergy. However, their ability to mitigate microplastic pollution in wastewater remains unexplored. This study showed that BES facilitated the treatment of polyethylene (PE), polyvinyl chloride (PVC), and Mix (PE+PVC) microplastic wastewater and the methane recovery (40.61%, 20.02%, 21.19%, respectively). The lactate dehydrogenase (LDH), adenosine triphosphate (ATP), cytochrome c, and nicotinamide adenine dinucleotide (NADH/NAD+) ratios were elevated with electrical stimulation. Moreover, the applied voltage improved the polysaccharides content of the extracellular polymeric substances (EPS) in the PE-BES but decreased in PVC-BES, while the proteins showed the opposite trend. Metatranscriptomic sequencing showed that the abundance of fermentation bacteria, acetogens, electrogens, and methanogens was greatly enhanced by applying voltage, especially at the anode. Methane metabolism was dominated by the acetoclastic methanogenic pathway, with the applied voltage promoting the enrichment of Methanothrix, resulting in the direct conversion of acetate to acetyl-CoA via acetate-CoA ligase (EC: 6.2.1.1), and increased metabolic activity in the anode. Moreover, applied voltage greatly boosted the function genes expression level related to energy metabolism, tricarboxylic acid (TCA) cycle, electron transport, and transporters on the anode biofilm. Overall, these results demonstrate that BES can mitigate microplastic pollution during wastewater treatment.

Exploring the flavor changes in mung bean flour through Lactobacillus fermentation: insights from volatile compounds and non-targeted metabolomics analysis.

Mung beans are highly nutritious but their leguminous flavor limits their development. Lactic acid bacteria (LAB) fermentation can decrease unwanted bean flavors in legumes and enhance their flavor. This study examined the influence of Lactobacillus fermentation on the flavor characteristics of mung bean flour (MBF) using volatile compounds and non-targeted metabolomics. Lactobacillus plantarum LP90, Lactobacillus casei LC89, and Lactobacillus acidophilus LA85 eliminated 61.37%, 48.29%, and 43.73%, respectively, of the primary bean odor aldehydes from MBF. The relative odor activity value (ROAV) results showed that fermented mung bean flour (FMBF) included volatile chemicals that contributed to fruity, flowery, and milky aromas. These compounds included ethyl acetate, hexyl formate, 3-hydroxy-2-butanone, and 2,3-butanedione. The levels of amino acids with a fresh sweet flavor increased significantly by 93.89, 49.40, and 35.27% in LP90, LC89, and LA85, respectively. A total of 49 up-regulated and 13 down-regulated significantly differential metabolites were annotated, and ten metabolic pathways were screened for contributing to the flavor. The correlation between important volatile compounds and non-volatile substances relies on two primary metabolic pathways: the citric acid cycle pathway and the amino acid metabolic system. The flavor of MBF was enhanced strongly by the process of Lactobacillus fermentation, with LP90 having the most notable impact. These results serve as a reference for identifying the flavor of FMBF. © 2024 Society of Chemical Industry.

The macroecology of butyrate-producing bacteria via metagenomic assessment of butyrate production capacity.

Butyrate-producing bacteria are found in many outdoor ecosystems and host organisms, including humans, and are vital to ecosystem functionality and human health. These bacteria ferment organic matter, producing the short-chain fatty acid butyrate. However, the macroecological influences on their biogeographical distribution remain poorly resolved. Here we aimed to characterise their global distribution together with key explanatory climatic, geographical and physicochemical variables. We developed new normalised butyrate production capacity (BPC) indices derived from global metagenomic (n = 13,078) and Australia-wide soil 16S rRNA (n = 1331) data, using Geographic Information System (GIS) and modelling techniques to detail their ecological and biogeographical associations. The highest median BPC scores were found in anoxic and fermentative environments, including the human (BPC = 2.99) and non-human animal gut (BPC = 2.91), and in some plant-soil systems (BPC = 2.33). Within plant-soil systems, roots (BPC = 2.50) and rhizospheres (BPC = 2.34) had the highest median BPC scores. Among soil samples, geographical and climatic variables had the strongest overall effects on BPC scores (variable importance score range = 0.30-0.03), with human population density also making a notable contribution (variable importance score = 0.20). Higher BPC scores were in soils from seasonally productive sandy rangelands, temperate rural residential areas and sites with moderate-to-high soil iron concentrations. Abundances of butyrate-producing bacteria in outdoor soils followed complex ecological patterns influenced by geography, climate, soil chemistry and hydrological fluctuations. These new macroecological insights further our understanding of the ecological patterns of outdoor butyrate-producing bacteria, with implications for emerging microbially focused ecological and human health policies.

Impact of a Whole-Food, High-Soluble Fiber Diet on the Gut-Muscle Axis in Aged Mice.

Previous studies have identified a role for the gut microbiome and its metabolic products, short-chain fatty acids (SCFAs), in the maintenance of muscle mass and physical function (i.e., the gut-muscle axis), but interventions aimed at positively impacting the gut-muscle axis during aging are sparse. Gut bacteria ferment soluble fiber into SCFAs, and accordingly, to evaluate the impact of a high-soluble-fiber diet (HSFD) on the gut-muscle axis, we fed a whole-food, 3×-higher-soluble fiber-containing diet (relative to standard chow) to aged (98 weeks) C57BL/6J mice for 10 weeks. The HSFD significantly altered gut bacterial community structure and composition, but plasma SCFAs were not different, and a positive impact on muscle-related measures (when normalized to body weight) was not identified. However, when evaluating sex differences between dietary groups, female (but not male) HSFD-fed mice had significant increases for SCFAs, the quadriceps/body weight (BW) ratio, and treadmill work performance (distance run × BW), which suggests that an HSFD can positively impact the gut-muscle axis. In contrast, consistent effects in both male and female HSFD-fed mice included weight and fat loss, which suggests a positive role for an HSFD on the gut-adipose axis in aged mice.

Enhanced Thermophilic Hydrogen Production by an Enriched Novel Acetic-Acid-Type Fermentative Bacterium from Inoculum Sludge with Nonheat Pretreatment

Enhanced Thermophilic Hydrogen Production by an Enriched Novel Acetic-Acid-Type Fermentative Bacterium from Inoculum Sludge with Nonheat Pretreatment

Exopolysaccharides isolated from fermented milk-associated lactic acid bacteria and applied to produce functional value-added probiotic yogurt

The current study aimed to isolate and characterize the lactic acid bacteria (LAB)-derived exopolysaccharide (EPS) and apply it to enhance yogurt's functional and technological quality. After screening and isolation of 52 different LAB strains from fermented milk products, Lactobacillus (L.) rhamnosus KF5, L. plantarum C182, Pediococcus (P.) acidilactici CCFM18, and Leuconostoc (Leu.) mesenteroides F27, with high EPS production yield, were nominated for further evaluation. EPS-derived strains were evaluated based on production yield, protein content, antioxidant activity, emulsification, and anti-inflammatory ability. After comparing isolated EPS samples, the Leu. mesenteroides F27 products were chosen in 3 concentrations (100, 250, and 500 mg EPS/L) to supplement the yogurt. EPS at all concentrations enhanced LAB growth, water-holding capacity, viscosity, and antioxidant activity. The electronic nose and tongue revealed that EPS did not affect the yogurt flavor profile. The confocal laser scanning microscopy showed a homogenously distributed protein and EPS network in the supplemented yogurt samples. However, in the rheology and consumer analysis, the 250 mg/L concentration showed better attributes, such as higher consistency, lower flow behavior, and a higher flavor score. Leu. mesenteroides F27-derived EPS could be used as a biological additive to enhance yogurt's technological and functional quality.

Enhancing bioelectrochemical hydrogen production from industrial wastewater using Ni-foam cathodes in a microbial electrolysis cell pilot plant

Microbial electrolysis cells (MECs) have garnered significant attention as a promising solution for industrial wastewater treatment, enabling the simultaneous degradation of organic compounds and biohydrogen production. Developing efficient and cost-effective cathodes to drive the hydrogen evolution reaction is central to the success of MECs as a sustainable technology. While numerous lab-scale experiments have been conducted to investigate different cathode materials, the transition to pilot-scale applications remains limited, leaving the actual performance of these scaled-up cathodes largely unknown. In this study, nickel-foam and stainless-steel wool cathodes were employed as catalysts to critically assess hydrogen production in a 150 L MEC pilot plant treating sugar-based industrial wastewater. Continuous hydrogen production was achieved in the reactor for more than 80 days, with a maximum COD removal efficiency of 40 %. Nickel-foam cathodes significantly enhanced hydrogen production and energy efficiency at non-limiting substrate concentration, yielding the maximum hydrogen production ever reported at pilot-scale (19.07 ± 0.46 L H2 m−2 d−1 and 0.21 ± 0.01 m3 m−3 d−1). This is a 3.0-fold improve in hydrogen production compared to the previous stainless-steel wool cathode. On the other hand, the higher price of Ni-foam compared to stainless-steel should also be considered, which may constrain its use in real applications. By carefully analysing the energy balance of the system, this study demonstrates that MECs have the potential to be net energy producers, in addition to effectively oxidize organic matter in wastewater. While higher applied potentials led to increased energy requirements, they also resulted in enhanced hydrogen production. For our system, a conservative applied potential range from 0.9 to 1.0 V was found to be optimal. Finally, the microbial community established on the anode was found to be a syntrophic consortium of exoelectrogenic and fermentative bacteria, predominantly Geobacter and Bacteroides, which appeared to be well-suited to transform complex organic matter into hydrogen.