Acetate Production Research Articles

Efficacy of Silica Solubilizing Bacteria as Plant Growth Promoting Rhizobacteria and Their Biochemical Characteristics

Twenty eight isolates of silica solubilising bacterial inoculants were collected from rhizosphere soils of rice crop in Kurnool, Prakasam, Guntur and Anantapur districts of Andhra Pradesh by using insoluble source of silica. These isolates were verified for plant growth promoting rhizobacteria (PGPR) activity and then subjected biochemical tests in the Department of Agricultural microbiology, Advanced Post Graduate Centre, ANGRAU, Lam, Guntur, Andhra Pradesh, India. Two isolates, SiKPP-1 (Silica solubilizing isolate from Kurnool district, Pamulapadu Mandal and Pamulapadu Village - 1) & SiPYY-3 (Silica solubilizing isolate from Prakasam district, Yerragondapalem Mandal and Yerragondapalem Village - 3) showed the highest efficiency in the aspects of silica solubilization, phosphate solubilization, potassium release, exopolysaccharide production activity, indole acetic acid production activity, siderophore production activity and biochemical tests including starch hydrolysis, Hydrogen sulphide test, Indole production, Catalase test, Oxidase test, Gelatine liquification, Methyl red test, Vogues Proskauer test, Citrate Utilization and Ammonia production. Therefore these two isolates (SiKPP-1&SiPYY-3) were selected for further pot and field studies in direct sown paddy crop.

An Environmentally Friendly Solvent for Cellulose Acetate Production: Ethyl Lactate

The aim of this study was to investigate the possibilities of using biodegradable ethyl lactate instead of acetic acid, the most preferred solvent in industrial production, during cellulose acetate synthesis under certain conditions. In the study, dissolving pulp fibres, which were activated with water and acetic acid respectively, were dispersed in ethyl lactate after pressing and then subjected to acetylation reaction with acetic anhydride catalysed by sulfuric acid. The properties of acetylated cellulose were determined using X-Ray diffraction analysis, Fourier-transform infrared spectroscopy, Differential Scanning Calorimetry and other chemical analysis methods (viscosity, the percentage of bounded acid, chemical resistance). It was determined that it was possible to produce cellulose acetate with a DS value of 2.79 in ethyl lactate at 40°C using dissolving pulp. Fourier-transform infrared spectroscopy studies revealed a characteristic band broadening in the 1739 cm-1 region, indicating the presence of acetyl groups. The results of X-ray diffraction analyses also showed that the crystalline structure of cellulose was completely dispersed and band broadenings on diffractograms occurred. However, the calculation made on X-ray diffractograms also provided interesting findings in terms of crystallite sizes. It was observed that the crystallite sizes of the acetates were higher compared to the dissolving pulp. It was determined that the high crystallinity of the samples posed a problem in terms of processing properties such as dissolution. Among the solvents used, only Dimethylsulfoxide was found to have sufficient dissolving power.

Genomic insight of phosphate solubilization and plant growth promotion of two taxonomically distinct winter crops by Enterobacter sp. DRP3.

Study of rhizospheric microbiome-mediated plant growth promotional attributes currently highlighted as a key tool for the development of suitable bio-inoculants for sustainable agriculture purposes. In this context, we have conducted a detailed study regarding the characterization of phosphate solubilizing potential by plant growth-promoting bacteria that have been isolated from the rhizosphere of a pteridophyte Dicranopteris sp., growing on the lateritic belt of West Bengal. We have isolated three potent bacterial strains, namely DRP1, DRP2, and DRP3 from the rhizoids-region of Dicranopteris sp. Among the isolated strains, DRP3 is found to have the highest phosphate solubilizing potentiality and is able to produce 655.89 and 627.58µg ml-1 soluble phosphate by solubilizing tricalcium phosphate (TCP) and Jordan rock phosphate, respectively. This strain is also able to solubilize Purulia rock phosphate moderately (133.51µg ml-1). Whole-genome sequencing and further analysis of the studied strain revealed the presence of pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase gdh gene along with several others that were well known for their role in phosphate solubilization. Further downstream, quantitative reverse transcriptase PCR-based expression study revealed 1.59-fold upregulation of PQQ-dependent gdh gene during the solubilization of TCP. Root colonization potential of the studied strain on two taxonomically distinct winter crops viz. Cicer arietinum and Triticum aestivum has been checked by using scanning electron microscopy. Other biochemical analyses for plant growth promotion traits including indole acetic acid production (132.02µg ml-1), potassium solubilization (3mg l-1), biofilm formation, and exopolymeric substances productions (1.88-2.03µg ml-1) also has been performed. This study highlighted the active involvement of PQQ-dependent gdh gene during phosphate solubilization from any Enterobacter group. Moreover, our study explored different roadmaps for sustainable farming methods and the preservation of food security without endangering soil health in the future.

Kilowatt-scale tandem CO2 electrolysis for enhanced acetate and ethylene production

Kilowatt-scale tandem CO2 electrolysis for enhanced acetate and ethylene production

Proteomic and metabolic analysis of Moorella thermoacetica-g-C3N4 nanocomposite system for artificial photosynthesis

Artificial photosynthesis by microbe-semiconductor biohybrid systems has been demonstrated as a valuable strategy in providing sustainable energy and in carbon fixation. However, most of the developed biohybrid systems for light harvesting employ heavy metal materials, especially cadmium sulfide (CdS), which normally cause environmental pollution and restrict the widespread of the systems. Herein, we constructed an environmentally friendly biohybirid system based on a typical acetogenic bacteria, Moorella thermoacetica, coupling with a carbon-based semiconductor, graphitic carbon nitride (g-C3N4), to realize light-driven carbon fixation. The proposed biohybrid system displayed outstanding acetate productivity with a quantum yield of 2.66 ± 0.43 %. Non-targeted proteomic analysis indicated that the physiological activity of the bacteria was improved, coupling with the non-toxic material. We further proposed the mechanisms of energy generation, electron transfer and CO2 fixation of the irradiated biohybrid system by proteomic and metabolomic characterization. With the photoelectron generated in g-C3N4 under illumination, CO2 is finally converted to acetate via the Wood-Ljungdahl pathway (WLP). Other associated pathways were also proved to be activated, providing extra energy or substrates for acetate production. The study reveals that the future focus of the development of biohybrid systems for light harvesting can be on the metal-free biocompatible material, which can activate the expression of the key enzymes involved in the electron transfer and carbon metabolism under light irradiation.

Interaction of a source rich in phytonutrients (fruits peel pellets) and polyunsaturated oil (Tung oil) on in vitro ruminal fermentation, methane production, and nutrient digestibility

Tropical fruit peels from mangosteen, rambutan, and banana are rich in phytonutrients. Several studies reported that the phytonutrients improved rumen fermentation. Nevertheless, the combination of phytonutrients and essential fatty acids on rumen fermentation have not yet been investigated. Hence, the aim of this research was to investigate the influence of fruit peel pellets (mangosteen, rambutan, and banana peel; MARABAC) containing phytonutrients and tung oil supplementation on rumen fermentation and the degradability of nutrients. Four levels of MARABAC (0, 2, 4, and 6 %) and four levels of tung oil (0, 2, 4, and 6 %) were supplemented with concentrate according to a 4 × 4 factorial arrangement in a completely randomized design (CRD). Rumen fermentation parameters, including gas production, ammonia nitrogen (NH3–N), volatile fatty acids (VFA), nutrient degradability (IVDMD and IVOMD), and in vitro methane (CH4) production were determined. The results showed that there were no interactions between MARABAC and Tung oil treatments for all terms of kinetic gas and cumulative gas, IVDMD and IVOMD, and in vitro ammonia-nitrogen (NH3–N). However, when combining MARABAC and tung oil beyond the 4 % level, VFA and in vitro CH4 production was severely affected. The supplementation of MARABAC and tung oil decreased gas production and rumen nutrient degradability (p < 0.05). Acetate (C2) and propionate (C3) production were significantly affected by the level of MARABAC supplementation. NH3–N was dropped when levels of MARABAC and tung oil supplementation were increased. There were interactions between MARABAC and tung oil on total VFA and in vitro CH4 production at 8 h (h). In addition, in vitro CH4 production decreased (p < 0.05) with higher levels of MARABAC supplementation. It could be concluded that MARABAC and tung oil supplementation significantly contributed to improving the production of gas and could be applied to decrease rumen CH4 production, thereby reducing the emission of greenhouse gases.

Bioaugmentation of Phanerochaete concrescens KS7 for enhanced growth and zinc nutrition in rice (Oryza sativa L.)

Bioaugmentation of microbial strains could act as sustainable intervention in soil for enhancing the availability of nutrients. Zinc deficiency is widely reported across the world and application of zinc based fertilizers mostly resulted in formation of unavailable zinc in soil. A fungus with zinc solubilisation was isolated from rice and identified as Phanerochaete concrescens KS7. Inoculation of fungus in culture medium resulted in decrease of pH to 4.4 and analysis of medium revealed higher content of citric and gluconic acid in comparison with uninoculated broth. Indole acetic acid production by the strain was found to be enhanced in presence of tryptophan under broth conditions. Zinc solubilisation potential of strain was quantified in medium amended with insoluble zinc source. There was enhanced root growth and significantly higher zinc concentration in rice seedling on inoculation with KS7. There was increase in plant height, leaf area, number of grains per panicle and grain yield per plant on inoculation with P. concrescens in two selected varieties of rice grown in zinc deficient soil. Partition analysis was done for zinc in root, stem and grains and there was significant increase of zinc content in rice grain on inoculation with KS7. Total and available zinc was quantified from soil after harvest of rice and found that zinc contents were higher in soil of KS7 inoculated plants. Phanerochaete concrescens KS7 could act as potential solubilizer of zinc in soil and improve the zinc content of crop produce especially in zinc deficient soils.

Exploring the mechanism of Weissella cibaria cooperating with Lactiplantibacillus plantarum to improve volatile flavor of Sichuan pickle using dialysis membranes

This study established a laboratory-scale dialysis membrane isolation device to explore bacterial cooperative fermentation mechanisms and their effects on pickle fermentation quality. Results showed the dialysis membranes with molecular weight cut-off of 1000 kDa was particularly effective in restricting Lactiplantibacillus plantarum LP067 and Weissella cibaria WC018 while facilitating nutrient and metabolite exchange. Our results showed that using dialysis membranes did not significantly affect the quality of cooperative fermentation Sichuan pickles. Using this dialysis membrane system, the Sichuan pickles of mono-inoculation or co-inoculation of Lactiplantibacillus plantarum LP067 or Weissella cibaria WC018 of the basic physicochemical index, organic acids, volatile flavor compounds, and sensory properties were evaluated. Compared to mono-inoculation of Lactiplantibacillus plantarum LP067 or Weissella cibaria WC018, co-inoculation accelerated acetic and lactic acids production, also significantly promoted the generation of volatile flavor compounds, such as esters, aldehydes, and ketones, including isobutyl formate, ethyl palmitate, ethyl acetate, 1-octen-3-ol and benzaldehyde. Meanwhile, cooperative fermentation increased the aroma complexity of Sichuan pickle, and thus to improve its overall sensory acceptability. The transcriptomic results revealed that W. cibaria WC018 enhanced the levels of genes related to lactic acid and acetic acid metabolism in L. plantarum LP067. The results provided a novel perspective for the isolation of individual strains in the cooperative fermentation process and laid a theoretical foundation to further explore the cooperative fermentation mechanisms among the same type strains.

The effect of silkworms (Bombyx mori) chitosan on rumen fermentation, methanogenesis, and microbial population in vitro.

Ruminant enteric methane (CH4) is one of the largest sources of greenhouse gases that contribute to global warming. To minimize environmental harm caused by ruminants' CH4 production, natural substances can be used to suppress it. Chitosan from crustacean sources had been known to obstruct CH4 generation in the rumen. About 18% of silkworm pupae is chitin, but little is known about the impact of silkworm pupae chitosan on rumen methanogenesis. This study investigated the efficacy of the silkworm chitosan extraction method and its impact on rumen fermentation, methanogenesis, and microbial growth in vitro. This study employed a randomized complete block design featuring five treatments and four batches for rumen incubation as the blocking factor. In this study, five treatments were implemented: Control (CO) (basal diet with no added chitosan), basal diet with 6% chitosan from the Chinese Silkworm strain 804 (CHI804), basal diet with 6% chitosan from the PS 01 Hybrid Silkworm strain (CHIPS01), basal diet with 6% chitosan from the Hybrid F1 Japanese 102 × Chinese 202 races (CHIJC02), and basal diet with 6% commercial shrimp shell chitosan as the positive control (CHICOMM). The in vitro experiments assessed digestibility, pH, total gas generation, CH4 production, ammonia nitrogen (NH3-N), and short-chain fatty acid levels, along with microbial population. Data were analyzed using a general linear model followed by Duncan's test when applicable. A significant effect on dry matter digestibility (DMD), total gas production, CH4, NH3-N, and rumen microbial populations (Methanogens, Ruminoccocus albus, Ruminoccocus flavefaciens, Selonomonas ruminantium, Butyrivibrio fibrisolvens, Streptoccocus bovis, Prevotella spp., and Bacteroides spp.) was observed (p < 0.05). The extracted chitosan (CHIJC02) used in this study exhibited a similar quality to that of commercial chitosan (CHICOMM). CHI804 treatment could reduce gas production, NH3-N production, and B. fibrisolvens population significantly (p < 0.05), while CHIJC02 could reduce CH4 production, methanogen population, acetate (C2) production, and increase propionate (C3) production significantly (p < 0.05). CHIJC02 and CHICOMM treatments could also increase the population of R. flavefaciens, S. ruminantium, and Bacteroides spp. significantly (p < 0.05). Chitosan addition significantly (p < 0.05) reduced DMD but did not impact organic matter digestibility or pH. The extracted chitosan mimics commercial chitosan in physico-chemical properties. Chitosan derived from Japanese and Chinese F1 hybrid silkworm strains demonstrated superior capacity for inhibiting CH4 generation compared to commercial chitosan. The quality and effects on methanogenesis, rumen fermentation, and rumen microbial populations can differ depending on the origin of chitosan.

Green Ca-source of cockle shells converted to calcium acetate for environmental sustainability

This work aimed to synthesize and characterize the calcium acetate monohydrate (Ca(CH3COO)2·H2O) from the exothermic reaction between CaCO3 powder derived from cockle shells with three different acetic acids (8, 10, and 12 mol L−1) concentrations by the rapid and easy process without pH and temperature control to lead to cheap chemical production. The physicochemical characteristics of all synthesized Ca(CH3COO)2·H2O samples are investigated based on the chemical compositions, crystal structures, vibrational characteristics, morphologies, and thermal behavior to confirm the target compound. A suitable concentration of 10 mol L−1 CH3COOH was chosen to produce Ca(CH3COO)2·H2O with the highest yield (96.30 %), maximum calcium content (96.2 % CaO) with lower impurities, and time consumption of 17 h. The calcium acetate product obtained from cockle shells in this work shows differences in thermal stability, morphological structure purity, %yield, and metal contamination with those reported obtained from other sources and another shell type in the previous work. This research investigates the transformation of cockle shell waste into CaCO3 for the production of calcium acetate, aiming to address environmental sustainability concerns by reducing the use of calcium ore resources and greenhouse gas emissions.

Demonstrating Pilot-Scale Gas Fermentation for Acetate Production from Biomass-Derived Syngas Streams

Gas fermentation is gaining attention as a crucial technology for converting gaseous feedstocks into value-added chemicals. Despite numerous efforts over the past decade to investigate these innovative processes at a lab scale, to date, the evaluation of the technologies in relevant industrial environments is scarce. This study examines the fermentative production of acetate from biomass-derived syngas using Moorella thermoacetica. A mobile gas fermentation pilot plant was coupled to a bubbling fluidized-bed gasifier with syngas purification to convert crushed bark-derived syngas. The syngas purification steps included hot filtration, catalytic reforming, and final syngas cleaning. Different latter configurations were evaluated to enable a simplified syngas cleaning configuration for microbial syngas conversion compared to conventional catalytic synthesis. Fermentation tests using ultra-cleaned syngas showed comparable microbial growth (1.3 g/L) and acetate production (22.3 g/L) to the benchmark fermentation of synthetic gases (1.2 g/L of biomass and 25.2 g/L of acetate). Additional fermentation trials on partially purified syngas streams identified H2S and HCN as the primary inhibitory compounds. They also indicated that caustic scrubbing is an adequate and simplified final gas cleaning step to facilitate extended microbial fermentation. Overall, this study shows the potential of gas fermentation to valorize crude gaseous feedstocks, such as industrial off-gases, into platform chemicals.

Preparation, characterization, and prebiotic potential of pectic oligosaccharide enzymatically derived from citric acid-extracted pumpkin pectic polysaccharide

Pectic polysaccharide from pumpkin pulp was enzymolyzed with Pectinex® Ultra SP-L. Afterward, the enzymolyzed pectic polysaccharide was fractionated into four fractions (Fraction 1, Fraction 2, Fraction 3, and Fraction 4) using dialysis tubes to elucidate the structural and physicochemical properties of pumpkin pectic oligosaccharide (PkPOS) with the most effective prebiotic potential. From the molecular weight (Mw) analysis, Fraction 1, Fraction 2, and Fraction 3 were classified as PkPOS (Mw of 1.47–4.09 kDa) and Fraction 4 as modified pectin (Mw mainly of 5.63–41.94 kDa). Combining the analysis results, a possible structure of each fraction was proposed as follows: Fraction 1 consisted mainly of galacturonic acid (GalA, 95.77%), most of which were presumably the reducing terminal α-GalA residues. Fraction 2, Fraction 3, and Fraction 4 consisted of the α-1,4-linked GalA residues and (substituted and/or unsubstituted) α-1,2-linked rhamnose (Rha) residues, indicating the presence of both the homogalacturonan and rhamnogalacturonan-I (RG-I) regions in their molecular structure. The proportion of the RG-I region was in descending order of Fraction 4 (GalA/Rha of 4.25) > Fraction 3 (GalA/Rha of 8.83) > Fraction 2 (GalA/Rha of 11.70). Among four fractions and fructooligosaccharides (FOS), Fraction 2 exhibited excellent stimulating effects on the growth of Lb. acidophilus, Lcb. rhamnosus GG, Lcb. casei, and Lcb. paracasei. Generally, Fraction 2 was the most effective in promoting the production of acetate. Although well-designed in vivo studies on prebiotic activities are needed, the present study suggests that Fraction 2 can be considered a promising candidate for a new generation of prebiotics.

Ethyl acetate production by Fischer esterification: use of excess of acetic acid and complete separation sequence

Abstract In this work, production of ethyl acetate (EtAc) using Fischer esterification between acetic acid (AcOH) and ethyl alcohol (EtOH) is presented. Batch kinetics was developed with EtOH as the limiting reactant to avoid the problems associated with unreacted ethanol in the final product. Regression was performed to estimate the parameters of the Langmuir Hinshelwood type kinetic equation. Reaction mass obtained during kinetics was subjected to separation and purification. Molecular sieves (MS) were used to remove water. Distillation (simple and extractive distillation – with entrainer, dimethyl sulfoxide, DMSO) was used to obtain almost pure AcOH, EtOH, EtAc and DMSO. Future work in reactive separation environment is indicated. Use of EtOH as the limiting reactant, use of MS for water removal and complete separation sequence are important features of this work.

In-situ biogenic FeS boosted acetate accumulation through CO2 capture and valorization using microbial electrosynthesis (MES)

Biosynthetic strategy of ferrous sulfide (FeS) through Shewanella oneidensis MR-1 in bioelectrochemical systems has been extensively explored to maintain bettered electron transfer performance. In this study, the simultaneous FeS biosynthesis and CO2 reduction were conducted in the microbial electrosynthesis (MES) system, aiming at improving electron transfer efficiency as well as acetate production. It was shown that the FeS was successfully biomineralized and then loaded onto the sludge in the Fe3+/S2O32−/MR-1 group, of which the acetate accumulation increased by 87.50%, 64.63% and 33.66% than the control, MR-1 and Fe3+/S2O32− groups. Also, electrochemical performance revealed by the CV analysis was enhanced, whereas the increased EPS accumulation and intracellular electron transfer activity by the biosynthesized FeS could also be proved. Moreover, the biogenic FeS enriched the abundances of acetogenic and sulfur-utilizing species as Acetobacterium, Clostridium_sensu_stricto_13, Sulfuricurvum and Desulfovibrio. Meanwhile, strongly positive correlations between Shewanella, the sulfur utilizers and acetogens were confirmed in the Fe3+/S2O32−/MR-1 group. With improved electron transfer efficiency and the boosted acetate accumulation, the in-situ biogenic FeS might be promising for CO2 capture and utilization.

Enrichment and characterization of human-associated mucin-degrading microbial consortia by sequential passage.

Mucin is a glycoprotein secreted throughout the mammalian gastrointestinal tract that can support endogenous microorganisms in the absence of complex polysaccharides. While several mucin-degrading bacteria have been identified, the interindividual differences in microbial communities capable of metabolizing this complex polymer are not well described. To determine whether community assembly on mucin is deterministic across individuals or whether taxonomically distinct but functionally similar mucin-degrading communities are selected across fecal inocula, we used a 10-day in vitro sequential batch culture fermentation from three human donors with mucin as the sole carbon source. For each donor, 16S rRNA gene amplicon sequencing was used to characterize microbial community succession, and the short-chain fatty acid profile was determined from the final community. All three communities reached a steady-state by day 7 in which the community composition stabilized. Taxonomic comparisons amongst communities revealed that one of the final communities had Desulfovibrio, another had Akkermansia, and all three shared other members, such as Bacteroides. Metabolic output differences were most notable for one of the donor's communities, with significantly less production of acetate and propionate than the other two communities. These findings demonstrate the feasibility of developing stable mucin-degrading communities with shared and unique taxa. Furthermore, the mechanisms and efficiencies of mucin degradation across individuals are important for understanding how this community-level process impacts human health.

Comparing the performance of fluidized and fixed granular activated carbon beds as cathodes for microbial electrosynthesis of carboxylates from CO2

Microbial electrosynthesis (MES) can use renewable electricity to power microbial conversion of carbon dioxide (CO2) into carboxylates. To ensure high productivities in MES, good mass transfer must be ensured, which could be accomplished with fluidization of granular activated carbon (GAC). In this study, fluidized and fixed GAC bed cathodes were compared. Acetate production rate and current density were 42 % and 47 % lower, respectively, in fluidized than fixed bed reactors. Although similar microbial consortium dominated by Eubacterium and Proteiniphilum was observed, lowest biomass quantity was measured with fixed GAC bed indicating higher specific acetate production rates compared to fluidized GAC bed. Furthermore, charge efficiency was the highest and charge recovery in carboxylates the lowest in fixed GAC beds indicating enhanced hydrogen evolution and need for enhancing CO2 feeding to enable higher production rates of acetate. Overall, fixed GAC beds have higher efficiency for acetate production in MES than fluidized GAC beds.

Interactive Effects of Dietary Fiber and Lipid Types Modulate the Predicted Production and Absorption of Cecal and Colorectal Short-Chain Fatty Acids in Growing Pigs

BackgroundHigh-fiber diets are supplemented with lipids to meet the required energy content, but data on the interactions between dietary fiber (DF) and lipid types on gastrointestinal fermentation in pigs are scant. ObjectivesThis study aimed to use a combination of in vivo and in vitro fermentation methodologies to determine the interactive effects of DF and lipid types on short-chain fatty acid (SCFA) production and absorption and organic matter (OM) fermentability in the cecum and colorectal tract of pigs. MethodsEight ileal- and cecal-cannulated Yorkshire barrows were fed either pectin- or cellulose-containing diets that were supplemented with either corn oil or beef tallow in 2 independent Youden squares with a 2 × 2 factorial arrangement of treatments (n = 6). Ileal and cecal digesta were collected, freeze-dried, and fermented using inoculum from fresh cecal digesta and feces, respectively, to determine individual SCFA production and absorption and fermentability of OM. ResultsInteractions (P < 0.001) between DF and lipid types were observed in which the addition of beef tallow decreased the quantity of cecal and colorectal acetic acid production and cecal acetic absorption, cecal butyric production, predicted cecal OM fermentability, and predicted colorectal propionic acid in pectin diets, but the effects were not observed for cellulose diets. The addition of beef tallow increased (P < 0.001) the production of cecal butyric and propionic acids during in vitro fermentation in cellulose diets and apparent total tract digestibility (ATTD) of OM in pectin diets. ConclusionsThe interactions between DF and lipids on gastrointestinal fermentation largely depend on the degree of saturation of fatty acids in dietary lipids. The addition of beef tallow selectively decreased the production and absorption of individual SCFAs in pectin and cellulose diets but increased cecal butyric and propionic acid production in cellulose diets and the ATTD of OM in pectin diets.

Isolation, screening, and characterization of the newly isolated osmotolerant yeast Wickerhamomyces anomalus BKK11-4 for the coproduction of glycerol and arabitol.

This study explored the isolation and screening of an osmotolerant yeast, Wickerhamomyces anomalus BKK11-4, which is proficient in utilizing renewable feedstocks for sugar alcohol production. In batch fermentation with high initial glucose concentrations, W. anomalus BKK11-4 exhibited notable production of glycerol and arabitol. The results of the medium optimization experiments revealed that trace elements, such as H3BO3, CuSO4, FeCl3, MnSO4, KI, H4MoNa2O4, and ZnSO4, did not increase glucose consumption or sugar alcohol production but substantially increased cell biomass. Osmotic stress, which was manipulated by varying initial glucose concentrations, influenced metabolic outcomes. Elevated glucose levels promoted glycerol and arabitol production while decreasing citric acid production. Agitation rates significantly impacted the kinetics, enhancing glucose utilization and metabolite production rates, particularly for glycerol, arabitol, and citric acid. The operational pH dictated the distribution of the end metabolites, with glycerol production slightly reduced at pH 6, while arabitol production remained unaffected. Citric acid production was observed at pH 6 and 7, and acetic acid production was observed at pH 7. Metabolomic analysis using GC/MS identified 29 metabolites, emphasizing the abundance of sugar/sugar alcohols. Heatmaps were generated to depict the variations in metabolite levels under different osmotic stress conditions, highlighting the intricate metabolic dynamics occurring post-glucose uptake, affecting pathways such as the pentose phosphate pathway and glycerolipid metabolism. These insights contribute to the optimization of W. anomalus BKK11-4 as a whole-cell factory for desirable products, demonstrating its potential applicability in sustainable sugar alcohol production from renewable feedstocks.

Optimized Feeding Strategies for Biosurfactant Production from Acetate by Alcanivorax borkumensis SK2

Biosurfactants are much-discussed alternatives to petro- and oleochemical surfactants. Alcanivorax borkumensis, a marine, Gram-negative γ-proteobacterium, produces a glycine-glucolipid biosurfactant from hydrocarbons, pyruvate, and acetate as carbon sources. Sustainable acetate production from lignocellulose or syngas adds to its relevance for the bioeconomy. This study investigated nitrogen sources and carbon-to-nitrogen ratios (C/N) to optimize fed-batch fermentation for biosurfactant production using A. borkumensis with acetate as the carbon source. Urea enabled high biosurfactant production, which was confirmed in DO-based fed-batch fermentation. Varying C/N ratios led to increased glycine-glucolipid production and decreased biomass production, with improvement plateauing at a C/N ratio of 26.7 Cmol Nmol−1. pH-stat fed-batch fermentation using glacial acetic acid as the carbon source and a pH-adjusting agent doubled the biosurfactant production. Finally, bubble-free membrane aeration was used to prevent extensive foam formation observed during conventional bubble aeration. The efficient production made it possible to investigate the bioactivity of glycine-glucolipid in combination with antibiotics against various microorganisms. Our findings allow for the leverage of glycine-glucolipid biosurfactant production using acetate as a carbon source.

Identification of lactic acid bacteria found in traditional Shalgam juice using 16S rRNA sequencing and evaluation of their probiotic potential in vitro

This research focuses on the identification of lactic acid bacteria (LAB) isolated from traditionally produced Shalgam juices collected from different locations in Türkiye and the characterization of their probiotic potential in vitro. LAB isolates were identified by 16 S rRNA gene sequencing. The most common strains belonged to Pediococcus acidilactici (54.2%), Lacticaseibacillus sp. (18.8%), L. paracasei (8.3%) and Enterococcus faecalis (6.3%). According to the test results, LAB isolates survived after exposure to low pH (2.0) except Levilactobacillus brevis TS9 and P. acidilactici TS10. All isolates showed tolerance to bile salts (69.78%–147.84%), pepsin (50.10%–159.43%), pancreatin (46.64%–120.12%) and phenol (58.19%–121.84%) at various levels. The isolates E. faecalis TS2 and Lacticaseibacillus sp. TS3 were more resistant to the target microorganisms. The isolates E. faecalis TS2, L. paracasei TS7, P. acidilactici TS41, and P. acidilactici TS43 were highly resistant to the antibiotics. The hydrophobicity of the isolates toward xylene ranged from 2.32% to 58.56% and P. acidilactici TS42 showed a high hydrophobicity of 58.56%. The ability of auto-aggregation and co-aggregation varied from 3.59% to 23.67% and 0.85–29.37%, respectively. The isolates showing the best probiotic properties (Lacticaseibacillus sp. TS3, Lacticaseibacillus sp. TS11, and L. paracasei TS33) were tested for their ability to produce short-chain fatty acids. The acetate, butyrate and propionate production of the isolates varied between 4040 and 8135, 1025–1255 and 14620-17225 μg/mL, respectively. Butyrate production of the isolates were higher than the control group. These results indicated that LAB originated from Shalgam juice could be proposed as probiotic candidates for use in fermented foods.