Fermented Slurry Research Articles

Microbial Community Dynamics and Metabolite Changes during Wheat Starch Slurry Fermentation.

Wheat starch fermentation slurry is the main substrate for producing Ganmianpi, a traditional Chinese fermented wheat starch-based noodle. In the present work, the microbial population dynamics and metabolite changes in wheat starch fermentation slurry at different fermentation times (0, 1, 2, 3, and 4 days) were measured by using high-throughput sequencing analysis and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) methods. The texture and sensory properties of Ganmianpi made from fermented starch slurry are also evaluated. The results showed that Latilactobacillus curvatus and Leuconostoc citreum were the dominant bacteria in wheat starch fermentation slurry, while Saccharomyces cerevisiae and Kazachstania wufongensis were identified as the main species of fungi. With the extension of fermentation time, the reducing sugar content first increased and then decreased, when the titratable acidity content showed an increasing trend, and the nonvolatile acid was significantly higher than the volatile acid. A total of 62 volatile flavor compounds were identified, and the highest content is alcohols, followed by acids. Fermentation significantly reduced the hardness and chewiness of Ganmianpi, and increased its resilience and cohesiveness. Ganmianpi made from fermented starch slurry for two and three days showed a higher sensory score than other samples. The present study is expected to provide a theoretical basis for exploiting the strains with potential for commercial application as starter cultures and quality improvement of Ganmianpi.

Enhancing volatile fatty acid production from food waste by H2O2-moderate temperature thermal pretreatment: Treating waste with waste in coal mining areas

Supplementing carbon sources in sewage treatment plants with organic matter from food waste is crucial for resource recycling in coal mining areas. In this study, a moderate-temperature H2O2 method was used to pretreat food waste from a coal mining area. The changes in the properties of the pretreated food waste and their influence on volatile fatty acids (VFAs) production during anaerobic fermentation were investigated. Additionally, the nitrogen and phosphorus removal rates obtained when glucose and fermentation slurry of food waste (FSFW) were used as carbon sources in the sewage treatment system were compared. Compared with untreated food waste, the soluble chemical oxygen demand (SCOD) increased by 58 % after pretreatment with 0.25 % H2O2 at 60 ℃, and the viscosity and oil content decreased significantly, which caused VFAs production to increase from 15,267 mg COD/L to 50,774 mg COD/L. When the H2O2 concentration increased to 2.0 %, the SCOD increased to 153 %, and the viscosity and oil content further decreased, but the VFAs production decreased to 7477 mg COD/L. This occurred because large quantities of ammonia nitrogen was formed at higher H2O2 doses, which inhibited VFAs formation. Moreover, the nitrogen removal rate was higher when FSFW was used as a carbon source than when glucose was used as a carbon source.

Pig slurry - A polydisperse substrate necessary for the biogasification of a lignite bed

The in situ transformation of the carbohydrate substances is presented in the context of methane (CH4) formation by methanogens. In situ coal conversion methods have been characterized due to the beneficial effect of unconventional coal mining. The research was carried out on less mature coals, with a lower carbonisation degree of organic matter, because they are more effective in conversion to bioenergy gas, which can be used for all pro-ecological activities. The original concept of experimental research was presented by combining the properties of a polydisperse substrate, which is pig slurry, and used for brown coal biogasification (anaerobic digestion) in two brown coal bed systems. For this purpose, a laboratory monosubstrate reactor for the fermentation of pig slurry in a lignite bed was developed. The mainaim of the research presented in the article is to assess the amount of agricultural biogas produced in the process of mesophilic methane fermentation with the use of a polydisperse substrate using a brown coal bed placed in a fermentor. The partial goals are:- presentation of analogies of techniques and methods of underground coal gasification (UCG) to biogasification of brown coal;- a set of correlation equations for calculating flow resistance coefficients through granular porous structures;- comparison of experimental values of flow resistance with calculations according to various models.The justification of the main goal and partial goals refers to the development of a new technique and method of obtaining biogas, taking into account the Reynolds number and the own model of the gas flow resistance coefficient.The novelty of the article are: developed own model for determining the correlation dependence of the flow resistance coefficient as a function of the Reynolds number, - the results of research that indicate the practical use of pig slurry in a lignite bed for which intensive biogas production takes place at lignite.- minor deposit in relation to lignite - flat fragments of a deposit. The inhibition phenomenon and the dynamics of the process during the production of biogas in the brown coal bed were also observed in the research. An additional advantage of the innovation in the article is the combination of a polydisperse substrate with a porous bed - the simplicity of the research is the production of biogas on a lignite bed, which is a medium for biogas-producing bacteria.It has been shown that:- the developed lignite biogasification system with the participation of a polydisperse substrate in the fermenter (laboratory vessel) ensures the production of biogas in the absence of thermal insulation of the fermenter;- for a lignite deposit, the biogas stream is stable with increasing temperature; while above the temperature of 38 °C–42 °C, the biogas stream is characterized by a downward trend.Comparing the flows of the biogas stream, the following can be observed:- the intensity of biogas production for lignite (smaller bed), there is a greater phase exchange, because the bed layout provides more space for the adhesion of methanogenic microorganisms, - in turn, in the case of lignite (flat fragments of the deposit), there is less phase exchange, i.e. less biogas production.The performed rheological tests of pig slurry proved the foaming properties of the sub-strate at 25 °C and 500 rpm for a kinematic viscosity of 27.5 mPa. Characteristic foaming properties are manifested by the polydisperse system, which is pig slurry.

An Assessment of the Development of a Mobile Agricultural Biogas Plant in the Context of a Cogeneration System

This article presents examples of cogeneration systems, which are standard equipment for biogas installations, based on the production of heat and electricity. It has been shown that in the case of microgeneration, ease of servicing and low installation costs are crucial. Characteristic aspects of developing concepts for mobile installations (small scale) that produce biogas, often with a simple container structure that is ready to be located in the economic infrastructure of the agricultural industry, were indicated. Recommendations for the operation of micro-biogas models are presented, which have the greatest impact on the advisability of using agricultural waste for energy purposes. A characteristic farm was selected, which has a substrate necessary for the process of methane fermentation of slurry from pig farming. The cogenerator, which constitutes a potential energy demand from the point of view of Polish agriculture in the context of renewable energy production, was analyzed. The research goal was to adapt the cogenerator to the conditions existing on a farm, which should meet the technical and technological expectations for the process of managing the produced methane with a value of 80% in agricultural biogas. The assessment of the impact of the amount of biogas on the level of CO, NO, NO2 and PM emissions was carried out at a constant engine speed for various load levels; the percentage of biogas was changed from 40 to approximately 70–80%, i.e., until significant knocking combustion was detected in the tested engines. As a result, the existing control and control system for the operation of the cogeneration unit prevents the most effective mode of operation of the research installation as a prosumer micro-installation. When the AG20P biogas unit operated in parallel with the grid with an active power of up to 11.7 kW, the electricity produced by the unit met the adopted assumptions and requirements. What is new in this article is the use of a cogeneration unit that has been adapted to its functionality, taking into account the assessment of the prospects for optimizing the cogeneration system in the context of the use of renewable energy sources as agricultural biogas. The best method was to attempt to determine the operating conditions of the cogenerator to develop the optimization of a biogas cogeneration unit producing electricity and heat in a micro-installation for the needs of an individual farm.

The regulation function of intestinal microbiota by folate-producing Lactiplantibacillus plantarum LZ227.

Folic acid is a class of B vitamins that have the function of improving intestinal microbiota. Lactiplantibacillus plantarum LZ227, which is a highly folate-producing strain, was used as the research object, and the folic acid produced by LZ227 was further identified by liquid chromatography-mass spectrometry, and the structural diversity, community composition, abundance difference, and short-chain fatty acids content in fermentation broth were studied by the manure slurry fermentation model. The results showed that the folic acid produced by LZ227 was 5-methyltetrahydrofolate. LZ227 can increase the intestinal microbial diversity in the folate-free state, regulate the intestinal flora, increase the abundance of Firmicutes in the intestinal flora, and inhibit the abundance of Bacteroidetes. LZ227 can inhibit the growth of Alistipes, Parabacteroides, and Bacteroides in the intestine. LZ227 significantly reduced the acetic acid content and significantly increased the butyric acid content in the folate-free case. © 2023 Society of Chemical Industry.

Effects of different strains fermentation on nutritional functional components and flavor compounds of sweet potato slurry.

In this paper, we study the effect of microbial fermentation on the nutrient composition and flavor of sweet potato slurry, different strains of Aspergillus niger, Saccharomyces cerevisiae, Lactobacillus plantarum, Bacillus coagulans, Bacillus subtilis, Lactobacillus acidophilus, and Bifidobacterium brevis were employed to ferment sweet potato slurry. After 48 h of fermentation with different strains (10% inoculation amount), we compared the effects of several strains on the nutritional and functional constituents (protein, soluble dietary fiber, organic acid, soluble sugar, total polyphenol, free amino acid, and sensory characteristics). The results demonstrated that the total sugar level of sweet potato slurry fell significantly after fermentation by various strains, indicating that these strains can utilize the nutritious components of sweet potato slurry for fermentation. The slurry's total protein and phenol concentrations increased significantly, and many strains demonstrated excellent fermentation performance. The pH of the slurry dropped from 6.78 to 3.28 to 5.95 after fermentation. The fermentation broth contained 17 free amino acids, and the change in free amino acid content is closely correlated with the flavor of the sweet potato fermentation slurry. The gas chromatography-mass spectrometry results reveal that microbial fermentation can effectively increase the kinds and concentration of flavor components in sweet potato slurry, enhancing its flavor and flavor profile. The results demonstrated that Aspergillus niger fermentation of sweet potato slurry might greatly enhance protein and total phenolic content, which is crucial in enhancing nutrition. However, Bacillus coagulans fermentation can enhance the concentration of free amino acids in sweet potato slurry by 64.83%, with a significant rise in fresh and sweet amino acids. After fermentation by Bacillus coagulans, the concentration of lactic acid and volatile flavor substances also achieved its highest level, which can considerably enhance its flavor. The above results showed that Aspergillus niger and Bacillus coagulans could be the ideal strains for sweet potato slurry fermentation.

Probiotic potential of Lactiplantibacillus plantarum ZFM4 isolated from pickles and its effects on human intestinal microecology

Lactic acid bacteria have received worldwide attention because of their fermentative properties and their great significance for the balance of microbial homeostasis in the intestine. In this study, we isolated a strain of Lactiplantibacillus plantarum ZFM4 from pickles and evaluated its probiotic properties. The results indicated that ZFM4 was suppressive to most pathogenic bacteria, especially Staphylococcus aureus and Pseudomonas aeruginosa, and showed good tolerance to high osmotic pressure (8.0% NaCl), high ethanol concentration (5.0%), high temperature (42 °C) and bile salts (0.3%, 4 h). The effect of ZFM4 on human intestinal microbiota was investigated through the fecal slurry fermentation model in vitro. Sequencing of the 16S rDNA gene demonstrated that the addition of ZFM4 significantly raised the abundance of phylum Bacillota, while increased the proportion of beneficial genera, such as Lactiplantibacillus and Bifidobacterium. Furthermore, ZFM4 contributed to the enhanced production of acetic acid, butyric acid, valeric acid, and isovaleric acid. In summary, ZFM4 could be considered a potential probiotic candidate.

Effects of self-produced lactic fermentation (SPLF) on GHG and VSC emissions during swine slurry storage

Self-produced lactic fermentation (SPLF) is a new valued utilization technology, but its impact on gas emission remains unclear. The objective of this study is to investigate the effect of replacing the H2SO4 additive with SPLF on greenhouse gas (GHG), and volatile sulfur compound (VSC) emissions from swine slurry storage in a laboratory-scale study. In this study, SPLF is directed toward producing lactic acid (LA) through the anaerobic fermentation of slurry and apple waste under the most suitable conditions, with the LA concentration kept at 10,000–52000 mg COD/L and the pH remaining within 4.5 during the following 90 days of slurry storage. Compared with that in the slurry storage treatment (CK), the GHG emissions decreased by 86% and 87% in the SPLF and H2SO4 groups, respectively. The low pH (i.e., less than 4.5) inhibited the growth of Methanocorpusculum and Methanosarcina and resulted in very low mcrA gene copies in the SPLF group, leading to a reduction in CH4 emissions. The methanethiol, dimethyl sulfide, dimethyl disulfide, and H2S emissions in the SPLF group were reduced by 57%, 42%, 22%, and 87% and increased by 2206%, 61%, 173%, and 1856% in the H2SO4 group, respectively. Therefore, SPLF can be an innovative bioacidification technology for effectively reducing GHG and VSC emissions from animal slurry storage.

Effective Fermentation of Sugarcane Bagasse Whole Slurries Using Robust Xylose-Capable Saccharomyces cerevisiae

The pre-treatment of lignocellulose material towards cellulosic bioethanol production releases microbial inhibitors that severely limit the fermentation ability of Saccharomyces cerevisiae. This study evaluated to what degree robust xylose-capable strains may improve the fermentability of non-detoxified sugarcane bagasse (SCB) slurries derived from steam explosion (StEX) and further compared this to slurries derived from ammonia fibre expansion (AFEX) pre-treatment. Initial screening in separate hydrolyses and co-fermentation processes using StEx-SCB hydrolysates identified S. cerevisiae TP-1 and CelluXTM4 with higher xylose consumption (≥ 88%) and ethanol concentrations (≥ 50 g/L), and ethanol metabolic yields (≥89% relative to theoretical maximum), even in the presence of approximately 8 g/L of acetic acid. Under industrially relevant pre-hydrolysis simultaneous saccharification and co-fermentation (PSSCF) conditions of high solids loading (15%, w/w) and low enzyme dosage (8 mg protein per gram untreated biomass), the fermentation of StEx-treated SCB whole slurry achieved ethanol yields of 208 and 224 L per Mg raw dry SCB using S. cerevisiae TP-1 and CelluXTM4, respectively. Under the same solids loading and enzyme dosages, the PSSCF of ammonia fibre expansion (AFEXTM) pre-treated SCB achieved ethanol yields of 234 and 251 L per Mg raw dry SCB using TP-1 and CelluXTM4, respectively. The study achieved non-detoxified whole-slurry co-fermentation using StEx pre-treated SCB, with higher ethanol yields than previously reported, by utilising robust xylose-capable strains. The results of this work provide insights into the potential use of inhibitor-tolerant S. cerevisiae strains TP-1 and CelluXTM4 as ethanologens for the fermentation of steam-exploded and undetoxified SCB whole slurries.

Optimizing the conditions of anaerobic fermentation in pig manure to produce volatile fatty acids and its efficiency in killing root-knot nematodes

To concurrently control root-knot nematodes and treat pig manure and further clarify the mechanism of anaerobic digestion slurries on nematodes, the optimal conditions for producing volatile fatty acids (VFAs) were studied, and the relationship between the carboxyl group in anaerobic fermentation and the mortality rate of root-knot nematodes was also researched. When the fermentation condition parameters were set as initial pH=10.0, temperature of 25 °C, and total solid (TS) loading of 15%, the largest quantity of VFA production was obtained through orthogonal experiments and range analyses. When the concentration of VFA in the anaerobic fermentation slurry was enhanced to 3.2 g/L, the rate of root-knot nematode mortality was up to 43.3% and was significantly different from that of the control. However, after the concentration of VFA reached 4.3 g/L, no significant difference was observed for the treatments with even higher concentrations of VFA. This indicated that the pig manure slurry with anaerobic digestion exhibited a limited range to kill root-knot nematodes. The results of this study provide a theoretical basis for producing acid from anaerobic digestion in pig manure and for slurry applications.

Efficient and practical bioconversion strategy of xylose-rich corncob for prebiotic Bacillus subtilis production

The probiotic of Bacillus subtilis ( B.subtilis ) is widely used in animal husbandry as a promising alternative to antibiotics, and a high value-added bioproduct from abundant and low-cost agricultural straws. For efficient fermentation of xylose-rich corncob slurry to B. subtilis cells, the step-by-step fermentation process (SSFP) and one-step fermentation process (OSFP) were proposed and compared by the combined technology of sulfuric acid pretreatment and enzymatic hydrolysis with cellulase . Xylose and glucose were fermented separately and sequentially in the SSFP route, while they were co-fermented in OSFP route. Here, B. subtilis performed an efficient bioconversion and almost fermented simultaneously glucose, xylose and arabinose in corncob slurry. We could obtain 326.8 g of B. subtilis in SSFP and 323.7 g probiotic cells in OSFP from 1000 g of corncob, respectively. In general, the OSFP route was preferable by virtue of a straightforward process and simple operation. • Preparation of probiotic B.subtilis from Agricultural straw. • B. subtilis almost fermented simultaneously C6 and C5 sugars in corncob slurry. • Xylose and glucose were fermented separately and sequentially in the SSFP route. • Xylose and glucose were co-fermented in OSFR route. • The OSFP process was used to obtain 323.70 g of B.subtilis from 1000 g of corncob.

Effectiveness of Hydrogen Production by Bacteroides vulgatus in Psychrophilic Fermentation of Cattle Slurry

H2 is a low-impact energy carrier, which the EU hydrogen strategy has positioned as a major component of energy policy. Dark fermentation by psychrophilic bacteria is a promising avenue of H2 production, though one that requires further study. The aim of this study was to determine the H2 production performance of a Bacteroides vulgatus strain during fermentation of psychrophilic cattle slurry. The test strain was isolated from an inland water body at a depth of 40 ± 5 m. The experimental fermentation process was run at 15 ± 1 °C and yielded 265.5 ± 31.2 cm3 biogas/g COD removed, including 46.9 ± 2.6 cm3 H2/g COD removed. CO2 was the main constituent of the resultant biogas, at 79.8 ± 1.9%. The gas also contained 17.6 ± 1.4% H2 and 2.3 ± 0.2% CH4. Organic matter removal and nutrient take-up from the feedstock were low. Our findings show that practical applicability of this process is hampered by multiple operational hurdles and its relatively poor performance.

Turbidity reduction in palm oil mill effluent (POME) by submerged fermentation with immobilized Aspergillus niger spores using coconut husk

Increasing production of palm oil in Malaysia has been releasing an alarming rate of palm oil mill effluent (POME). POME must be treated prior to release into the environment. Turbidity reduction by fermentation in palm oil mill effluent (POME) reduces the chemical oxygen demand (COD) which improves the effectiveness of downstream treatment. Aspergillus niger is a promising decomposer but as a filamentous fungus, its performance could be enhanced when it is supported with fibrous surface to provide a larger surface area for growth. Waste material from agroindustry constituted from lignocellulose have been widely used in the immobilization process to reduce costs. In the present study, sterile coconut husk was used to immobilize A.niger cells. POME, the fermentation media was prepared at concentrations ranging from 0-100%. Post fermentation slurry was filtered. Turbidity for every concentration were recorded. A free cell fermentation was conducted for comparison. The immobilized cell fermentation shows turbidity reduction between 95% and 98% while the free cell fermentation shows reduction between 87% and 95%. The immobilized cell produced a better turbidity reduction percentage.

Anti-Diarrhea Effects of OGI Produced Using Saccharomyces Boulardii As Starter Culture

The antidiarrhea effect of 96 hr fermented ‘Ogi’ (Corn slurry) using Saccharomyces boulardii as starter culture against Escherichia coli was investigated in-vitro and in-vivo using Wistar rats. The pH and titratable acid of the slurry were determined, while the antimicrobial effect on diarrhea causing organisms, Escherichia coli was also determined. Using well diffusion method, 0.1 ml of the slurry effectively inhibited the growth of E. coli with zones of inhibition ranging from 2.4 (±0.14)a mm at 24hr of fermentation to 8.4(±0.11)d mm at 96hr of fermentation. The zones of inhibition increased with increasing period of fermentation of the filtrate which is Ogi. The titratable acidity of the fermenting Guinea corn increased with increasing period of fermentation and reached a peak at 96hr of fermentation (0.25 (± 0.02)c %). The pH however decreased with increase in the period of fermentation from 5.65 (± 0.01)a at 0hr to 3.54 (± 0.02)e at 96hr of fermentation. The antidiarrheal activity of Guinea corn slurry was investigated in-vivo using E. coli to induce diarrhea. The infected test groups of rats were fed orographically with fermented slurry of Guinea corn (Ogi), whereas positive control group was neither being infected nor fed with ogi while negative control group was infected with E. coli but not fed with Ogi. In test groups fed with fermented ‘Ogi’ recovered from diarrhea infection. The obtained results of the present study confirm the possibility of using fermented guinea corn slurry (Ogi) produced using Saccharomyces boulardii as starter culture for the treatment of diarrhea rather than the organisms in drug presentation which reduces compliance in diarrheal patients most especially children.

Mechanism of Electron Acceptor Promoting Propionic Acid Transformation in Anaerobic Fermentation

To improve the conversion efficiency of propionic acid in the post-anaerobic fermentation of biogas slurry, the anaerobic fermentation process using biogas slurry with a high acid content was simulated in an anaerobic reactor at 35 ± 0.5 °C using sodium propionate as the sole substrate. The effects of different electron acceptors (NO3−, SO42− and Fe3+) on propionic acid conversion and the succession of microbial community structures were investigated. The results showed that the experimental group with the electron acceptor NO3− exhibited the best anaerobic fermentation effect, with a maximum propionate removal rate of 94%, which was 36% higher than the control group without an electron acceptor. The maximum methane production rate was 307.6 mL/g COD, an increase of 30% compared with the control group. Thauera, Aquabacterium, Desulfomicrobium, Clostridium_sensu_stricto_1, and other functional microorganisms were all enriched. The dominant functional genes related to redox reactions, such as K03711, K00384, and K03406, were highly enriched in the reactor when Fe3+ and NO3− were added. The study shows that adding an electron acceptor can enhance interactions between microorganisms, achieve efficient propionate conversion, and improve methane production in the system.

Evaluation of the nutritional composition and acceptability of powdered ogi enriched with date palm fruits

This study was carried out to evaluate the nutritional composition and acceptability of powdered ogi enriched with date palm fruits. Ogi is a fermented slurry made with maize. Ogi enriched with date palm fruits was formulated in order to develop a nutrient dense product and an alternative to the available products, by increasing the usage of these crop materials. The prepared powdered ogi (POD) was enriched with the inclusion of different proportions of powdered dates (0, 5, 10 and 15%, which were labeled control, POD1, POD2 and POD3 respectively). Proximate analysis and sensory evaluation were then carried out on the samples. The results showed that there was a significant difference (p< 0.05) in the proximate composition of the enriched ogi samples, with sample POD3 having relatively higher values for ash (12.07%) and crude fibre (3.51%) when compared to the control. From the result of the mineral analysis, the concentration of minerals (Na, K, Fe, and P) increased significantly (p<0.05) with increasing level of dates, with POD3 having the highest concentration of P (768.16 ppm), K (728.00 ppm) and Fe (127.00 ppm). POD2 had a significantly high (p<0.05) concentration of Na (146.00 ppm). The sensory properties of the samples were generally liked by the panelist, but the overall acceptability of POD3 was highly rated and preferred. This study revealed that the enriched samples were nutrient dense and therefore recommended for homes to alleviate hidden hunger.

Kinetic Modeling of Peroxydisulfate Pre-Treatment of Algae Slurry (Pasir Gudang, Malaysia) for Increasing Methane Generation from Anaerobic Digestion: Fertilizer Recovery

This study looked into the possibility of using peroxydisulfate pretreatment to enhance biogas production from anaerobic fermentation of algal slurry. The results demonstrate that a peroxydisulfate added system with a dose of 0.02 g peroxydisulfate/g algal sludge TSS produces the most accumulative methane after 61 days of fermentation. At 0.02, 0.03, 0.06, 0.2, 0.3, 0.6, and 1.2 g peroxydisulfate/g algal sludge TSS cumulative methane generation was 1.16, 1.09, 1.15, 1.14, 1.09, 0.77, and 0.16 times higher than control. After 120 minutes of pre-treatment, the SCOD in the system continued to rise when the peroxydisulfate dosage was enhanced. To simulate the methane yield, a one-substrate model might be utilized. After dosing with peroxydisulfate, the hydrolysis rate reduced, and the maximum resultant and anticipated cumulative methane output was achieved with 0.02 g peroxydisulfate/g algal sludge TSS. After digestion, microcystin-LR in algae slurry was mostly eliminated. Heavy metals could be released from algae cells into the effluent as a result of the greater peroxydisulfate dosage. From the fermented effluent, sludge recapture was 0.09 m3 sludge/m3. The supplementation of peroxydisulfate to algae slurry may boost cumulative methane generation while also lowering microcystin-LR levels.

Kefir Culture-Mediated Fermentation to Improve Phenolic-Linked Antioxidant, Anti-Hyperglycemic and Human Gut Health Benefits in Sprouted Food Barley

The bioprocessing strategy is an effective approach to improve bioavailability and stability of bioactive compounds for designing functional foods and ingredients. In this study, food barley was bio-transformed to improve functional bioactives by sprouting, coupled with beneficial lactic acid bacteria (LAB)-based fermentation. Dairy Kefir culture with mixed beneficial LAB strains was targeted to ferment aqueous slurries of sprouted hulless food barley flour (unpigmented, purple, and black barley) for 72 h, and modulation of phenolic-linked antioxidant and anti-hyperglycemic functionalities were evaluated using in vitro assay models. The biochemical parameters analyzed were total soluble phenolic (TSP) content, profile of phenolic compounds, total antioxidant activity, and anti-hyperglycemic property-relevant α-amylase and α-glucosidase enzyme inhibitory activities. Furthermore, human gut health benefits of relevant properties of fermented slurries of barley flour were also evaluated based on growth of Kefir culture and subsequent determination of anti-bacterial potential against pathogenic human ulcer causing bacteria Helicobacter pylori. Kefir culture-mediated fermentation of 48-h sprouted barley flours improved the TSP content and associated antioxidant and anti-hyperglycemic functionalities. Additionally, anti-bacterial potential against H. pylori and sustaining active growth of viable LAB cells above the minimum level required for probiotic activity were also observed in fermented food barley flour slurries.

Integrated Chemical Biochemical Technology to Reduce Ammonia Emission from Fermented Municipal Biowaste

A new eco-friendly process is reported, the implementation of which at the EU level could reduce ammonia and greenhouse gas emissions from fermented biowaste by over 1 Gt yr–1. The present work reports the case study of municipal biowaste (MBW). The process is based on the use of soluble bio-organic substances (SBOs) as auxiliaries in the anaerobic fermentation of MBW to produce biogas and digestate with reduced ammonia content. The SBO-assisted process enables a virtuous biowaste cycle, where MBW is sequentially fermented under anoxic conditions, the digestate is composted, and the compost generated is hydrolyzed, yielding SBO, which is recycled to the anaerobic fermentation reactor at 0.2% concentration. The results show that depending on the MBW source, fermentation inoculum, and SBO concentration in the fermentation slurry, about 40% reduction of ammonium in the digestate is achieved, whereas the control fermentation without SBO exhibits up to 11% ammonia increase. The microbial community and biogas production are not significantly affected by SBO addition. The data are consistent with biological and chemical processes occurring in SBO-assisted fermentation. These comprise ammonia production by protein hydrolysis catalyzed by proteolytic bacteria and ammonia oxidation to N2 catalyzed by SBOs. The results confirm the benefit provided by the use of SBOs to reduce the environmental impact of biowaste. These encourage the implementation of SBO-assisted fermentation in the real operational environment.

The α-Helical Cap Domain of a Novel Esterase from Gut Alistipes shahii Shaping the Substrate-Binding Pocket.

The human gut microbiota regulates nutritional metabolism, especially by encoding specific ferulic acid esterases (FAEs) to release functional ferulic acid (FA) from dietary fiber. In our previous study, we observed seven upregulated FAE genes during in vitro fecal slurry fermentation using wheat bran. Here, a 29 kDa FAE (AsFAE) from Alistipes shahii of Bacteroides was characterized and identified as the type-A FAE. The X-ray structure of AsFAE has been determined, revealing a unique α-helical domain comprising five α-helices, which was first characterized in FAEs from the gut microbiota. Further molecular docking analysis and biochemical studies revealed that Tyr100, Thr122, Tyr219, and Ile220 are essential for substrate binding and catalytic efficiency. Additionally, Glu129 and Lys130 in the cap domain shaped the substrate-binding pocket and affected the substrate preference. This is the first report on A. shahii FAE, providing a theoretical basis for the dietary metabolism in the human gut.