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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Effect of dietary fiber fermentation on short‐chain fatty acid production and microbial composition in vitro

Abstract BACKGROUND The efficient utilization of fiber‐rich co‐products is important for optimizing feed resource utilization and animal health. This study was conducted to evaluate the fermentation characteristics of fiber‐rich co‐products, which had equal quantities of total dietary fiber (TDF), at different time points using batch in vitro methods. It considered their gas production, short‐chain fatty acid (SCFA) production, and microbial composition. RESULTS The fermentation of wheat bran (WB) and oat bran (OB) showed higher and faster ( P < 0.05) gas and SCFA production than corn bran (CB), sugar beet pulp (SBP), and soybean hulls (SH). The α ‐diversity was higher in the CB, SBP, and SH groups than in the WB and OB groups ( P < 0.05). At the phylum level, OB and WB fermentation showed lower ( P < 0.05) relative abundance of Actinobacteria than the CB, SBP, and SH groups. At the genus level, OB and WB fermentation increased the Enterococcus population in comparison with the CB, SBP, and SH groups, whereas CB and SBP fermentation improved the relative abundance of the Christensenellaceae R‐7 group more than the WB, OB, and SH groups ( P < 0.05). CONCLUSION Overall, WB and OB were rapidly fermented by fecal microbiota, in contrast with SBP, SH, and CB. Fermentation of different fiber‐rich co‐products with an equal TDF content gives different responses in terms of microbial composition and SCFA production due to variations in their physicochemical properties and molecular structure. © 2020 Society of Chemical Industry

Bai, Yu↗
DOE OSTI2023

Effects of Saccharomyces cerevisiae quorum sensing signal molecules on ethanol production in bioethanol fermentation process

Here in this study, the concentrations of Saccharomyces cerevisiae quorum sensing signal molecules (QSMs) were determined, not to mention the exploration of the effects of exogenous S. cerevisiae QSMs on the sole fermentation of S. cerevisiae and co-fermentation of S. cerevisiae and Lactobacillus plantarum. The results showed that the concentrations of three signal molecules (2-phenylethanol (2-PE), tyrosol and tryptophan) produced by S. cerevisiae increased with a higher bacteria density, which tends to become stable up to 118.02, 32.05 and 1.93 mg/L respectively when cultivating for 144 h. Among the three signaling molecules, only 2-PE promoted the ethanol production capacity of S. cerevisiae. The ethanol concentration of the sole fermentation of S. cerevisiae loaded with 120 mg/L 2-PE reached 3.2 g/L in 9 h, which was 58.7% higher than that of the group without 2-PE addition. Moreover, 2-PE reduced the negative impact of L. plantarum on S. cerevisiae. Within 12 h of the co-fermentation of L. plantarum and S. cerevisiae, the ethanol concentration in the co-fermentation group loaded with 2-PE reached 5.6 g/L, similar to that in the group fermenting with sole S. cerevisiae, and the yeast budding rate was also restored to 28.51%. qRT-PCR results of S. cerevisiae which was in sole fermentation with 2-PE addition for 9 h showed that the relative expression levels of ethanol dehydrogenase gene ADH1 in S. cerevisiae decreased by 25% and the relative expression levels of MLS1, CIT2, IDH1,CIT1 decreased by 26%, 30%, 22%,18%, respectively, meant that the glyoxylic and tricarboxylic acid cycles were greatly inhibited, which promotes the accumulation of ethanol. The results of this study provide basic data for using QSMs more than antibiotics in the the prevention of contamination during the industrialized bioethanol production.

2-phenylethanol↗
DOE OSTI2022

Extracellular electron transfer increases fermentation in lactic acid bacteria via a hybrid metabolism

Energy conservation in microorganisms is classically categorized into respiration and fermentation; however, recent work shows some species can use mixed or alternative bioenergetic strategies. We explored the use of extracellular electron transfer for energy conservation in diverse lactic acid bacteria (LAB), microorganisms that mainly rely on fermentative metabolism and are important in food fermentations. The LAB Lactiplantibacillus plantarum uses extracellular electron transfer to increase its NAD + /NADH ratio, generate more ATP through substrate-level phosphorylation, and accumulate biomass more rapidly. This novel, hybrid metabolism is dependent on a type-II NADH dehydrogenase (Ndh2) and conditionally requires a flavin-binding extracellular lipoprotein (PplA) under laboratory conditions. It confers increased fermentation product yield, metabolic flux, and environmental acidification in laboratory media and during kale juice fermentation. The discovery of a single pathway that simultaneously blends features of fermentation and respiration in a primarily fermentative microorganism expands our knowledge of energy conservation and provides immediate biotechnology applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Fermentation‐mediated growth, signaling, and defense in plants

Summary While traditionally considered important mainly in hypoxic roots during flooding, upregulation of fermentation pathways in plants has recently been described as an evolutionarily conserved drought survival strategy, with acetate signaling mediating reprograming of transcription and cellular carbon and energy metabolism from roots to leaves. The amount of acetate produced directly correlates with survival through potential mechanisms including defense gene activation, biosynthesis of primary and secondary metabolites, and aerobic respiration. Here, we review root ethanolic fermentation responses to hypoxia during saturated soil conditions and summarize studies highlighting acetate fermentation under aerobic conditions coupled with respiration during growth and drought responses. Recent work is discussed demonstrating long‐distance transport of acetate via the transpiration stream as a respiratory substrate. While maintenance and growth respiration are often modeled separately in terrestrial models, here we propose the concept of ‘Defense Respiration’ fueled by acetate fermentation in which upregulation of acetate fermentation contributes acetate substrate for alternative energy production via aerobic respiration, biosynthesis of primary and secondary metabolites, and the acetylation of proteins involved in defense gene regulation. Finally, we highlight new frontiers in leaf‐atmosphere emission measurements as a potential way to study acetate fermentation responses of individual leaves, branches, ecosystems, and regions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Antioxidant Activity, Microbiological Quality, and Acceptability of Spontaneously Fermented Shrimp Sausage (Litopenaeus vannamei)

Fermented shrimp sausages are prepared spontaneously with Litopenaeus vannamei as raw material. Shrimp is one of the marine sources with rich chitosan as bioactive compounds, antioxidants, vitamin E, and probiotic lactic acid bacteria (LAB) produced by fermentation processes. This study aimed to analyze the variations in antioxidant activity, vitamin E content, total LAB, total pathogenic bacteria, pH, and acceptability of shrimp sausage produced at different fermentation times. A completely randomized experimental design study was performed using four levels of exposure time, including control (0 days), 1, 2, and 3 days. The treatment was conducted spontaneously with 1.2% salt concentration, a drying temperature of 50°C for 3 h, and fermentation at 35°C. The evaluated parameters included the antioxidant activity measured with the radical 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) method, vitamin E levels by high-performance liquid chromatography, total LAB with total plate count, and Escherichia coli bacteria by the most probable number method. Salmonella sp. and Staphylococcus aureus were estimated by the identification method. A pH meter was used to assess acidity, and hedonic organoleptic testing was performed for taste, aroma, color, and texture. The results show significant differences in antioxidant activity, vitamin E, and shrimp sausage acceptability at varied fermentation times p ≤ 0.05 . However, the best formulation was obtained with the first-day fermented shrimp sausage, as shown by its bioactive content and the level of acceptability.

Afifah, Diana N.↗
DOE OSTI2023

An integrated biorefinery approach to obtain xylo-oligosaccharides from corncob using lactic acid-rich fermentation broth

Although xylo-oligosaccharides production from lignocelluloses via lactic acid hydrolysis is advantageous in terms of high yields with less by-products, the use of high purity lactic acid inevitably increases the cost of xylo-oligosaccharides production. The utilization of lactic acid-rich fermentation broth for xylo-oligosaccharides production can avoid the separation and purification of lactic acid. However, the feasibility of lactic acid-rich fermentation broth for xylo-oligosaccharides production from lignocelluloses was unclear. In this work, the results indicated that the highest xylo-oligosaccharides yield of 72% was obtained from corncob by lactic acid-rich fermentation broth pretreatment and xylanase hydrolysis. Subsequently, monosaccharides-rich hydrolysate (90.9 g/L) was obtained from solid residues of corncob by cellulase hydrolysis. Lactic acid-rich fermentation broth was produced by Weizmannia coagulans fermentation of the monosaccharide-rich hydrolysate. Besides, the obtained xylo-oligosaccharides and lactic acid mixture might be used as feed additives, avoiding the purification and separation of lactic acid or xylo-oligosaccharides. Meanwhile, the production cost of feed grade xylo-oligosaccharides from this work was much lower than the current market price. Overall, this work proposed a new strategy for efficient and environmental-friendly production of xylo-oligosaccharides from corncob.

09 BIOMASS FUELS↗
DOE OSTI2024

Oxygenation influences xylose fermentation and gene expression in the yeast genera Spathaspora and Scheffersomyces

Abstract Background Cost-effective production of biofuels from lignocellulose requires the fermentation of d -xylose. Many yeast species within and closely related to the genera Spathaspora and Scheffersomyces (both of the order Serinales) natively assimilate and ferment xylose. Other species consume xylose inefficiently, leading to extracellular accumulation of xylitol. Xylitol excretion is thought to be due to the different cofactor requirements of the first two steps of xylose metabolism. Xylose reductase (XR) generally uses NADPH to reduce xylose to xylitol, while xylitol dehydrogenase (XDH) generally uses NAD + to oxidize xylitol to xylulose, creating an imbalanced redox pathway. This imbalance is thought to be particularly consequential in hypoxic or anoxic environments. Results We screened the growth of xylose-fermenting yeast species in high and moderate aeration and identified both ethanol producers and xylitol producers. Selected species were further characterized for their XR and XDH cofactor preferences by enzyme assays and gene expression patterns by RNA-Seq. Our data revealed that xylose metabolism is more redox balanced in some species, but it is strongly affected by oxygen levels. Under high aeration, most species switched from ethanol production to xylitol accumulation, despite the availability of ample oxygen to accept electrons from NADH. This switch was followed by decreases in enzyme activity and the expression of genes related to xylose metabolism, suggesting that bottlenecks in xylose fermentation are not always due to cofactor preferences. Finally, we expressed XYL genes from multiple Scheffersomyces species in a strain of Saccharomyces cerevisiae . Recombinant S. cerevisiae expressing XYL1 from Scheffersomyces xylosifermentans , which encodes an XR without a cofactor preference, showed improved anaerobic growth on xylose as the primary carbon source compared to S. cerevisiae strain expressing XYL genes from Scheffersomyces stipitis . Conclusion Collectively, our data do not support the hypothesis that xylitol accumulation occurs primarily due to differences in cofactor preferences between xylose reductase and xylitol dehydrogenase; instead, gene expression plays a major role in response to oxygen levels. We have also identified the yeast Sc. xylosifermentans as a potential source for genes that can be engineered into S. cerevisiae to improve xylose fermentation and biofuel production.

09 BIOMASS FUELS↗
DOE OSTI2021

Diverse Profile of Fermentation Byproducts From Thin Stillage

The economy of biorefineries is influenced not only by biofuel production from carbohydrates but also by the production of valuable compounds from largely underutilized industrial residues. Currently, the demand for many chemicals that could be made in a biorefinery, such as succinic acid (SA), medium-chain fatty acids (MCFAs), and lactic acid (LA), is fulfilled using petroleum, palm oil, or pure carbohydrates as raw materials, respectively. Thin stillage (TS), the residual liquid material following distillation of ethanol, is an underutilized coproduct from the starch biofuel industry. This carbon-rich material has the potential for chemical upgrading by microorganisms. Here, we explored the formation of different fermentation products by microbial communities grown on TS using different bioreactor conditions. At the baseline operational condition (6-day retention time, pH 5.5, 35°C), we observed a mixture of MCFAs as the principal fermentation products. Operation of a bioreactor with a 1-day retention time induced an increase in SA production, and a temperature increase to 55°C resulted in the accumulation of lactic and propionic acids. In addition, a reactor operated with a 1-day retention time at 55°C conditions resulted in LA accumulation as the main fermentation product. The prominent members of the microbial community in each reactor were assessed by 16S rRNA gene amplicon sequencing and phylogenetic analysis. Under all operating conditions, members of the Lactobacillaceae family within Firmicutes and the Acetobacteraceae family within Proteobacteria were ubiquitous. Members of the Prevotellaceae family within Bacteroidetes and Lachnospiraceae family within the Clostridiales order of Firmicutes were mostly abundant at 35°C and not abundant in the microbial communities of the TS reactors incubated at 55°C. The ability to adjust bioreactor operating conditions to select for microbial communities with different fermentation product profiles offers new strategies to explore and compare potentially valuable fermentation products from TS and allows industries the flexibility to adapt and switch chemical production based on market prices and demands.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Combined effects of lipase and Lactiplantibacillus plantarum 1‐24‐LJ on physicochemical property, microbial succession and volatile compounds formation in fermented fish product

Abstract BACKGROUND Studies have shown that either the addition of starter culture or enzyme can improve fermentation in fish or other products. However, little research has been carried out on the effects of coupling starter cultures with lipase on the microbial community and product quality. Suanzhayu is a Chinese fermented fish product that mainly relies on spontaneous fermentation, resulting in an unstable flavor and quality. The present study investigated the impact of lipase and Lactiplantibacillus plantarum 1‐24‐LJ on the quality of Suanzhayu . RESULTS Inoculation decreased pH and 2‐thiobarbituric acid reactive substances (TBARS) values, and also helped the dominance of the strain in the ecosystem, whereas lipase addition raised TBARS values and had little effect on pH, water activity ( a w ) and microbiota. The addition of lipase and/or Lpb. plantarum increased the content of alcohols, aldehydes, ketones, esters and umami amino acids. The co‐additions with the most significant effect and the total contents of volatile compounds (VCs) and free amino acids (FAAs) were 1801.92 g per 100 g and 21 357.05 mg per 100 g, respectively. Former‐ Lactobacillus was negatively correlated with pH, a w and Prevotella , but positively with VCs (ethyl ester of heptanoic acid, ethyl ester of octanoic acid) and FAAs (Tyr, Phe). Furthermore, adding Lpb. plantarum 1‐24‐LJ alone or in combination with lipase shortened the fermentation process. CONCLUSION The present study provides a recommended Suanzhayu process approach for improving product quality and flavor, as well as shortening fermentation time, by adding Lpb. plantarum 1‐24‐LJ with or without lipase. © 2023 Society of Chemical Industry.

Zhang, Zuoli↗
DOE OSTI2023

Enhanced, continuous, liquid-liquid extraction and in-situ separation of volatile fatty acids from fermentation broth

In 2018 alone, the US landfilled 35.3 million tons of food waste, about 24% of the total landfilled mass. In addition to the negative impacts landfills have demonstrated on the environment and human health, some states have begun to outlaw or dissuade the disposal of food waste and sewage sludge into landfills altogether. An urgent need has thus been created for the development of digestion processes like anaerobic digestion (AD) and arrested methanogenesis (AM) to convert food waste into valuable chemical products. Unfortunately, the buildup of volatile fatty acids (VFAs) during these processes eventually halts the reaction, and energy efficient methodologies for VFA removal are critical for the operation of fermenters. Additionally, VFAs themselves can serve as valuable chemical precursors, and recently AD processes have been modified to increase VFA production during fermentation. However, even with significant research over the past three decades, the separation of VFAs from the fermenter broth has remained expensive. Moreover, the separation of these VFAs from the fermenter broth may cost up to 50% of the entire process budget, hindering the widespread commercial adoption of AD and AM. Here we present a novel liquid-liquid extraction process termed CLEANS (Continuous Liquid-liquid Extraction And iN-situ Separation) as a highly efficient method for continuously separating VFAs from a real fermentation broth solely under gravity. Our optimized process (using an aqueous broth feed pH of 2.5, tri-noctylamine as an extractant, and a 10:1 ratio of aqueous broth to organic extractant), achieved a VFA distribution constant K D = 44.5 ± 7.9, a single-pass recovery = 81.3 ± 2.5%, and an extraction factor = 8.1 ± 0.3. These KD values are over an order of magnitude higher than what has been previously reported for comparable processes. A high aqueous-to-organic flowrate ratio, enabled for the first time by CLEANS, was found to be particularly crucial for achieving optimal extraction. Our separation process demonstrates excellent reproducibility and potential for scalability. The economic and environmental implications of this work are briefly discussed.

42 ENGINEERING↗
DOE OSTI2024

Compositional and temporal division of labor modulates mixed sugar fermentation by an engineered yeast consortium

Abstract Synthetic microbial communities have emerged as an attractive route for chemical bioprocessing. They are argued to be superior to single strains through microbial division of labor (DOL), but the exact mechanism by which DOL confers advantages remains unclear. Here, we utilize a synthetic Saccharomyces cerevisiae consortium along with mathematical modeling to achieve tunable mixed sugar fermentation to overcome the limitations of single-strain fermentation. The consortium involves two strains with each specializing in glucose or xylose utilization for ethanol production. By controlling initial community composition, DOL allows fine tuning of fermentation dynamics and product generation. By altering inoculation delay, DOL provides additional programmability to parallelly regulate fermentation characteristics and product yield. Mathematical models capture observed experimental findings and further offer guidance for subsequent fermentation optimization. This study demonstrates the functional potential of DOL in bioprocessing and provides insight into the rational design of engineered ecosystems for various applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Switchgrass Steroidal Saponins Reduce Fungal Disease but Decrease Yeast Fermentation Yield

Increasing the production of bioproducts from lignocellulosic feedstocks requires improvement in both field production and biorefinery efficiency. When plant traits arise that improve field production but decrease biofuel yield, these trade-offs can represent challenges in the entire production process. To examine trade-offs between field and production traits, we examined factors underlying switchgrass resistance to fungal rust pathogens in field conditions and factors that impede yeast fermentation in the lab using repeated measurements on a switchgrass genetic diversity panel. We found that the same switchgrass genotypes that showed high fungal pathogen resistance also showed recalcitrance to yeast fermentation. These switchgrass genotypes were mostly from the Atlantic genetic group, which had high levels of specialized metabolites of the saponin class. Among 1589 metabolites identified through metabolomics, we found that saponins were among the most likely to explain variation in both rust infection and fermentation yield using random forest feature selection, and that only four of these were sufficient to explain 57.9% of the variation in rust susceptibility. Through follow-up testing in recalcitrant biomass, we found that the bacterium Zymomonas mobilis does not suffer the same inhibition as the yeast Saccharomyces cerevisiae, and that the addition of ergosterol (thought to be the fungal cellular target of saponin inhibition) rescues yeast fermentation. Several lines of evidence point to a central role for saponins as key metabolites protecting switchgrass from fungal pathogens and interfering with yeast fermentation, underscoring an ongoing need for collaboration between plant breeders and biofuel production scientists.

VanWallendael, Acer [North Carolina State Universi↗
DOE OSTI2021

Coculture with hemicellulose-fermenting microbes reverses inhibition of corn fiber solubilization by Clostridium thermocellum at elevated solids loadings

Abstract Background The cellulolytic thermophile Clostridium thermocellum is an important biocatalyst due to its ability to solubilize lignocellulosic feedstocks without the need for pretreatment or exogenous enzyme addition. At low concentrations of substrate, C. thermocellum can solubilize corn fiber > 95% in 5 days, but solubilization declines markedly at substrate concentrations higher than 20 g/L. This differs for model cellulose like Avicel, on which the maximum solubilization rate increases in proportion to substrate concentration. The goal of this study was to examine fermentation at increasing corn fiber concentrations and investigate possible reasons for declining performance. Results The rate of growth of C. thermocellum on corn fiber, inferred from CipA scaffoldin levels measured by LC–MS/MS, showed very little increase with increasing solids loading. To test for inhibition, we evaluated the effects of spent broth on growth and cellulase activity. The liquids remaining after corn fiber fermentation were found to be strongly inhibitory to growth on cellobiose, a substrate that does not require cellulose hydrolysis. Additionally, the hydrolytic activity of C. thermocellum cellulase was also reduced to less-than half by adding spent broth. Noting that > 15 g/L hemicellulose oligosaccharides accumulated in the spent broth of a 40 g/L corn fiber fermentation, we tested the effect of various model carbohydrates on growth on cellobiose and Avicel. Some compounds like xylooligosaccharides caused a decline in cellulolytic activity and a reduction in the maximum solubilization rate on Avicel. However, there were no relevant model compounds that could replicate the strong inhibition by spent broth on C. thermocellum growth on cellobiose. Cocultures of C. thermocellum with hemicellulose-consuming partners— Herbinix spp. strain LL1355 and Thermoanaerobacterium thermosaccharolyticum —exhibited lower levels of unfermented hemicellulose hydrolysis products, a doubling of the maximum solubilization rate, and final solubilization increased from 67 to 93%. Conclusions This study documents inhibition of C. thermocellum with increasing corn fiber concentration and demonstrates inhibition of cellulase activity by xylooligosaccharides, but further work is needed to understand why growth on cellobiose was inhibited by corn fiber fermentation broth. Our results support the importance of hemicellulose-utilizing coculture partners to augment C. thermocellum in the fermentation of lignocellulosic feedstocks at high solids loading.

09 BIOMASS FUELS↗
DOE OSTI2024

Effect of Temperature and pH on Microbial Communities Fermenting a Dairy Coproduct Mixture

Organic-rich industrial residues can serve as renewable feedstocks for the generation of useful products by microbial fermentation. We investigated fermenting communities enriched in a mixture of ultra-filtered milk permeate (UFMP) and acid whey from cottage cheese (CAW), two dairy coproducts rich in lactose. To evaluate how operational pH and temperature affect microbial communities and fermentation products, we operated 12 bioreactors for 140 days, each fed a 1:1 mixture of UFMP and CAW at either 35 °C or 50 °C and at either a pH of 4.8 or 5.5. The bioreactors operated at a pH of 4.8 resulted in the incomplete conversion of lactose, while those operated at a pH of 5.5 consistently fermented lactose, primarily into lactic, acetic, and hexanoic acids. The metagenomic analyses revealed that microbial communities obtained at a pH of 5.5 were dominated by lactic acid-producing organisms. Additionally, an inverse relationship was found between the abundance of chain elongating organisms and lactic acid accumulation, with 50 °C reducing the abundance of these organisms and enhancing lactic acid yields. We conclude that the pH and temperature are important determinants of the fermentation of dairy coproducts with a pH of 5.5 and 50 °C yielding the most promising results for lactic acid production. Additional research is required to better understand the factors affecting functional consistency of the process.

Biotechnology & Applied Microbiology↗
DOE OSTI2023

Valorisation of Wasted Immature Tomato to Innovative Fermented Functional Foods

In this study, the lactic fermentation of immature tomatoes as a tool for food ingredient production was evaluated as a circular economy-oriented alternative for valorising industrial tomatoes that are unsuitable for processing and which have wasted away in large quantities in the field. Two lactic acid bacteria (LAB) were assessed as starter cultures in an immature tomato pulp fermentation to produce functional food ingredients with probiotic potential. The first trial evaluated the probiotic character of Lactiplantibacillus plantarum (LAB97, isolated from immature tomato microbiota) and Weissella paramesenteroides (C1090, from the INIAV collection) through in vitro gastrointestinal digestion simulation. The results showed that LAB97 and C1090 met the probiotic potential viability criterion by maintaining 6 log10 CFU/mL counts after in vitro simulation. The second trial assessed the LAB starters’ fermentative ability. Partially decontaminated (110 °C/2 min) immature tomato pulp was used to prepare the individually inoculated samples (Id: LAB97 and C1090). Non-inoculated samples, both with and without thermal treatment (Id: CTR-TT and CTR-NTT, respectively), were prepared as the controls. Fermentation was undertaken (25 °C, 100 rpm) for 14 days. Throughout storage (0, 24, 48, 72 h, 7, and 14 days), all the samples were tested for LAB and Y&M counts, titratable acidity (TA), solid soluble content (SSC), total phenolic content (TPC), antioxidant capacity (AOx), as well as for organic acids and phenolic profiles, and CIELab colour and sensory evaluation (14th day). The LAB growth reached ca. 9 log10 CFU/mL for all samples after 72 h. The LAB97 samples had an earlier and higher acidification rate than the remaining ones, and they were highly correlated to lactic acid increments. The inoculated samples showed a faster and higher decrease rate in their SSC levels when compared to the controls. A nearly two-fold increase (p < 0.05) during the fermentation, over time, was observed in all samples’ AOx and TPC (p < 0.05, r = 0.93; similar pattern). The LAB97 samples obtained the best sensory acceptance for flavour and overall appreciation scores when compared to the others. In conclusion, the L. plantarum LAB97 starter culture was selected as a novel probiotic candidate to obtain a potential probiotic ingredient from immature tomato fruits.

Pereira, Nelson (ORCID:0000000345745615)↗
DOE OSTI2025

Modeling the Impacts of Hydrogen Extraction on Anaerobic Fermentation Systems Using a Modified ADM1 Model

Here, this paper presents a modified ADM1 (mADM1) model for use in assessing the influence of active dissolved H 2 extraction on biogas production from anaerobic fermentation reactors, specifically in the context of high-strength brewery wastewater as the feed. The modified model adds regulation factors to account for the varying product stoichiometry of glucose degradation reactions as a function of H 2 concentration in anaerobic digestion, and incorporates the use of both lactate and ethanol as intermediates. The changes to the model are expected to better predict the effects of H 2 removal on the production of H 2 in fermentation processes. Both ADM1 and mADM1 were calibrated against experimental data from a fluidized-bed reactor containing encapsulated acidogenic-acetogenic microbial communities treating real brewery wastewater. The calibrated models were validated against another fluidized-bed reactor identical to the calibration reactor, with the addition of a hollow-fiber membrane module that was used to reduce dissolved H 2 concentrations in the validation reactor. It was found that ADM1 over-estimated the H 2 production rates of the validation reactor (117 mL/day simulated vs. 16.48 mL/day experimental), whereas mADM1 was able to successfully predict fermentation, and specifically the H 2 production rate (17 mL/day). The presented model is a first step towards a model that can predict the effects of dissolved H 2 removal on fermentation processes.

Anaerobic Digestion↗
DOE OSTI2025

Resourceful and economical designing of fermentation medium for lab and commercial strains of yeast from alternative feedstock: ‘transgenic oilcane’

Sugarcane plant engineered to accumulate lipids in its vegetative tissue is being developed as a new bioenergy crop. The new crop would be a source of juice, oil, and cellulosic sugars. However, limited tolerance of industrially recognized yeasts towards inhibitors generated during the processing of lignocellulosic biomass to produce fermentable sugars is a major challenge in developing scalable processes for second-generation drop-in fuel production. To this end, hydrolysates generated from engineered sugarcane—‘oilcane’ bagasse contain added phenolics and fatty acids that further restrict the growth of fermenting microorganisms and necessitate nutrient supplementation and/or detoxification of hydrolysate which makes the fermentation process expensive. Herein, we propose a resourceful and economical approach for growing lab and commercial strains of S. cerevisiae on unrefined cellulosic sugars aerobically and fermentatively.

09 BIOMASS FUELS↗
DOE OSTI2021

Exogenous Enzymes Influenced Eimeria-Induced Changes in Cecal Fermentation Profile and Gene Expression of Nutrient Transporters in Broiler Chickens

Two 21-day experiments were conducted to investigate the effects of exogenous enzymes on growth performance, tight junctions, and nutrient transporters, jejunal oligosaccharides and cecal short-chain fatty acids (SCFA) of broiler chickens challenged with mixed Eimeria. Two different basal diets: high fiber-adequate protein (HFAP; Expt. 1) or low fiber-low protein (LFLP; Expt. 2) were used in the two experiments. In each experiment, birds were allocated to four treatments in a 2 × 2 factorial arrangement (with or without protease and xylanase combination; with or without Eimeria challenge). In Expt. 1, with HFAP diets, Eimeria upregulated (p < 0.05) the expression of claudin-1, but downregulated (p < 0.05) glucose transporters GLUT2/GLUT5. On the contrary, enzymes downregulated (p < 0.05) claudin-1 and alleviated the Eimeria-depressed GLUT2/GLUT5 expression. In both experiments, Eimeria decreased (p < 0.05) cecal saccharolytic SCFA and increased (p < 0.05) cecal branched-chain fatty acids. The challenge × enzyme interaction (p < 0.05) showed that enzymes reversed the Eimeria effects on fermentation pattern shift. In conclusion, Eimeria altered tight junctions and nutrient transporters expression promoted cecal proteolytic fermentation and inhibited saccharolytic fermentation. Exogenous enzymes showed the potential of alleviating the Eimeria-induced intestinal gene expression changes and reversing the unfavorable cecal fermentation pattern.

59 BASIC BIOLOGICAL SCIENCES↗