Propionate Production Research Articles

PSI-13 Effects of a Postbiotic Program Consisting of Liquid and Solid Saccharomyces Cerevisiae Fermentation Products on Ruminal Microbiome Composition and Microbial Functions of Finishing Beef Steers

Abstract We assessed the effects of a postbiotic program consisting of liquid and solid Saccharomyces cerevisiae fermentation products (SCFP) on the ruminal microbiome and fermentation characteristics of beef steers. Eight Holstein steers (BW 467 ± 13.9 kg) with rumen cannulas were used in a crossover design study with 21-d per period and 7-d washout in between periods. Steers were blocked based on initial BW and assigned to one of two treatments: 1) Control, basal diet, or 2) SCFP, basal diet plus one day feeding of LiquiCare RTU (Diamond V, Cedar Rapids, IA; dosed via rumen cannula at 11 mL/100 kg BW), followed by daily feeding of 12 g/d NaturSafe (Diamond V, top-dressed). Rumen fluid samples were collected on d 0, 1, 2, 3, 5 and 21 at 0, 4, 8, or 12 h post morning feeding via rumen cannula for pH, VFA and NH3-N analyses. Samples collected at 4 h post morning feeding on d 0, 2 and 21 were subjected to DNA extraction and shotgun Nanopore sequencing to determine microbiome composition and carbohydrate active enzymes (CAZy) functional potential. Statistical model included the fixed effects of treatment, period, day and their interactions and random effect of animal. Feeding SCFP tended to reduce ruminal lactate (0.09 vs. 0.02 mM, P = 0.10), and reduced ruminal NH3-N (4.86 vs. 6.83 mg/dL, P = 0.04) on d 21. Ruminal total VFA concentration was increased (P = 0.01) by feeding SCFP 4-h post-feeding on d 5 and numerically increased 4-h post-feeding on day 21 (133.3 vs. 151.2 mM, P = 0.12). Treatments did not affect species or CAZy alpha- and beta-diversity. Steers received liquid postbiotic on d 2 exhibited a positive correlation (P < 0.05) between propionate molar proportion and glycosyl transferases (GT), glycoside hydrolases (GH), carbohydrate esterases, and carbohydrate binding modules (CBM); and a negative correlation (P < 0.05) between acetate molar proportion and polysaccharide lyases, GT, GH, and CBM, which was not observed in Control. Additionally, SCFP steers had higher (P = 0.05) CBM functional potential on d 21 than on d 0, while CAZy class abundances did not change over time in Control steers. Differential network analysis indicated a greater normalized degree for GT in the SCFP steers compared with Control on d 21. There were 2, 6 and 12 differently abundant species (P < 0.01) between SCFP and Control on d 0, 2 and 21, respectively, suggesting supplementing SCFP altered the abundances of more species over time. Our results showed that the postbiotic program altered the metabolic pathways of ruminal microbes toward greater propionate production, and improved abundance of carbohydrate binding modules. Our results also showed that glycosyl transferases had a greater promotive role in the ruminal enzymatic network of SCFP steers.

Unrevealing the in vitro impacts of Cereus jacamaru DC. cladodes flour on potentially probiotic strains, selected bacterial populations, and metabolic activity of human intestinal microbiota

This study investigated the potential impacts of the flour from Cereus jamacaru cactus cladodes (CJF), a cactus native to the Brazilian Caatinga biome, on the growth and metabolism of different potentially probiotic strains, as well as on the abundance of selected intestinal bacterial populations and microbial metabolic activity during in vitro colonic fermentation with a pooled human fecal inoculum. Cultivation of the probiotics in a medium with C. jamacaru cladodes flour (20 g/L) resulted in viable cell counts of up to 9.8 log CFU/mL, positive prebiotic activity scores (0.73–0.91), decreased pH and sugar contents, and increased lactic, acetic, and propionic acid production over time, indicating enhanced probiotic growth and metabolic activity. CJF overall increased the relative abundance of Lactobacillus spp./Enterococcus spp. (2.12–3.29%) and Bifidobacterium spp. (4.08–4.32%) and decreased the relative abundance of Bacteroides spp./Prevotella spp. (8.35–6.81%), Clostridium histolyticum (6.91–3.59%), and Eubacterium rectale/Clostridium coccoides (7.70–3.95%) during 48 h of an in vitro colonic fermentation using a pooled human fecal inoculum. CJF stimulated the microbial metabolic activity, with decreased pH, sugar consumption, lactic and short-chain fatty acid production, alterations in overall metabolic profiling and phenolic compound contents, and maintenance of high antioxidant capacity during colonic fermentation. These results show that CJF stimulated the growth and metabolic activity of distinct potential probiotics, increased the relative abundance of beneficial intestinal bacterial groups, and stimulated microbial metabolism during in vitro colonic fermentation. Further studies using advanced molecular technologies and in vivo experimental models could forward the investigation of the potential prebiotic properties of CJF.

Microbially catalyzed anode and cathode microbial electrosynthesis system for efficient metformin removal and volatile fatty acid production

The removal of different pharmaceuticals and personal care products from surface water is crucial. This study focused on the removal and transformation of metformin (MTF), an emerging contaminant in aqueous solutions using a dual biocatalyzed microbial electrosynthesis system (MES). Successful biodegradation of MTF (91 %) was achieved within 120 h with improved bioelectrochemical performance. The current density (−849 mA/m2) with drug loading at 0.5 ppm was 10.3, 7.6, and 2.4 times higher than that of the control, 0.1 ppm, and 0.3, ppm, respectively. Volatile fatty acids (VFAs) production also improved with excellent acetate, propionate, and butyrate production at dual biocatalyzed MES. Liquid chromatography mass spectrometry studies indicated improved mineralization with more MTF bioproducts. MTF regulated the microbial flora through enrichment of the electroactive phyla Proteobacteria and Bacteroidetes. This study provides a new perspective for the use of dual biocatalyzed microbial electrosynthesis systems in bioremediation research.

Preweaning period is a critical window for rumen microbial regulation of average daily gain in Holstein heifer calves.

Rumen bacterial groups can affect growth performance, such as average daily gain (ADG), feed intake, and efficiency. The study aimed to investigate the inter-relationship of rumen bacterial composition, rumen fermentation indicators, serum indicators, and growth performance of Holstein heifer calves with different ADG. Twelve calves were chosen from a trail with 60 calves and divided into higher ADG (HADG, high pre- and post-weaning ADG, n = 6) and lower ADG (LADG, low pre- and post-weaning ADG, n = 6) groups to investigate differences in bacterial composition and functions and host phenotype. During the preweaning period, the relative abundances of propionate producers, including g_norank_f_Butyricicoccaceae, g_Pyramidobacter, and g_norank_f_norank_o_Clostridia_vadinBB60_group, were higher in HADG calves (LDA > 2, P < 0.05). Enrichment of these bacteria resulted in increased levels of propionate, a gluconeogenic precursor, in preweaning HADG calves (adjusted P < 0.05), which consequently raised serum glucose concentrations (adjusted P < 0.05). In contrast, the relative abundances of rumen bacteria in post-weaning HADG calves did not exert this effect. Moreover, no significant differences were observed in rumen fermentation parameters and serum indices between the two groups. The findings of this study revealed that the preweaning period is the window of opportunity for rumen bacteria to regulate the ADG of calves.

Microencapsulation of Mitragyna leaf extracts to be used as a bioactive compound source to enhance in vitro fermentation characteristics and microbial dynamics.

Mitragyna speciosa Korth is traditionally used in Thailand. They have a high level of antioxidant capacities and bioactive compounds, the potential to modulate rumen fermentation and decrease methane production. The aim of the study was to investigate the different levels of microencapsulated-Mitragyna leaves extracts (MMLE) supplementation on nutrient degradability, rumen ecology, microbial dynamics, and methane production in an in vitro study. A completely randomized design was used to assign the experimental treatments, MMLE was supplemented at 0%, 4%, 6%, and 8% of the total dry matter (DM) substrate. The addition of MMLE significantly increased in vitro dry matter degradability both at 12, 24, and 48 h, while ammonia-nitrogen (NH3-N) concentration was improved with MMLE supplementation. The MMLE had the greatest propionate and total volatile fatty acid production when added with 6% of total DM substrate, while decreased the methane production (12, 24, and 48 h). Furthermore, the microbial population of cellulolytic bacteria and Butyrivibrio fibrisolvens were increased, whilst Methanobacteriales was decreased with MMLE feeding. The results indicated that MMLE could be a potential alternative plant-based bioactive compound supplement to be used as ruminant feed additives.

PSI-19 A Saccharomyces Cerevisiae-Derived Postbiotic Stimulates in Vitro Volatile Fatty Acid Production and Influences Hindgut Microbial Population Characteristics

Abstract Horses rely on volatile fatty acids (VFA) to provide a source of energy and fermentative end-products for their health and performance. Improvement in VFA production, has been associated in various species with improved feed conversion and availability of nutrients necessary to maintain epithelial cell growth, blood flow, and the normal secretory and absorptive functions of the intestine and positive changes in the microbial ecology of the gut. In this study, we characterized the effect of a dietary Saccharomyces cerevisiae fermentation postbiotic (SCFP; Diamond V, Cedar Rapids, IA) using an in vitro equine intestinal model to estimate the effects on VFA production and microbiome changes in the horse hindgut. Treatments contained inoculated medium containing a predigested blend of alfalfa and timothy hay substrate and a dilution of fresh equine excreta. The test article (SCFP) was evaluated at 150 mg (TEC) and 225 mg (TECP), in addition to a negative control containing inoculated medium alone, and the positive control containing inulin. The full array of treatments and replicates were incubated anaerobically at 37.2 C for 24 h. VFA concentrations were analyzed by gas chromatography and the microbiome was characterized through shotgun sequencing. Both levels of SCFP supported greater (P &amp;lt; 0.05) acetate, propionate, butyrate, and total VFA production versus the negative control. Greater production of acetate, propionate, butyrate and total VFA was observed for TECP compared with the positive control (P &amp;lt; 0.05). Between the two SCFP treatments, TECP promoted more acetate, propionate and total VFA (P &amp;lt; 0.01), and 18.3% more butyrate than TEC. Significant microbiome changes were also observed, with TEC and TECP promoting greater microbiome diversity (P &amp;lt; 0.05) compared with both negative and positive controls. Compared with the negative control, both levels of SCFP influenced an increased abundance (P &amp;lt; 0.05) of lactic acid producers (Veillonella), butyrate producers (Butyricicoccus, Anaerobutyricum), and an increased abundance of multiple Bacteroides species, all known for their enrichment of carbohydrate-degrading enzymes. Interestingly, our data show a distinct effect of inulin in microbial communities by promoting an increased abundance of Streptococcus species. This study provides evidence that a SCFP can stimulate VFA production, and this effect is incremental with the level of administration which could potentially provide gut health benefits in horses.

211 Evaluating the Influence of Soybean Meal and its Bioactive Compounds on Nutrient Utilization, Fermentation, and Gastrointestinal Metabolites of Nursery Pigs

Abstract Recently soybean meal (SBM) has garnered more attention due to its increased feeding value during periods of stress and improved bioavailable energy. However, the influence of the innate bioactive compounds in SBM on the microbiome and fermentation products have not been fully elucidated. Thus, the experimental objective was to investigate the mechanism of action of SBM and its bioactive compounds in the gastrointestinal tract of nursery pigs. Two replications of 18 barrows (8.12 ± 0.80 kg BW; PIC800 × Camborough; n = 36), were randomly assigned to a dietary treatment of either a high SBM positive control (SBMC; 28.6%), a negative control void of SBM (SP), but included soy protein isolate and concentrate to provide amino acids from soy protein the same as SBM in SBMC; SP formulated to the same contribution and composition of isoflavones as SBMC (SP+ISO; 528 mg/kg of soy-isoflavones); SP diet fortified with soybean functional lipids of lecithin and phytosterols at similar concentration in SBMC (SP+LIP; 2.85 g/kg of functional lipids); SP formulated to the same contribution and ratio of insoluble to soluble fiber as SBM in SBMC (SP+FIB; 30 g/kg of soy fiber); or SP diet fortified with lunasin peptide at 3.81 g/kg (SP+LUN). Pigs were individually housed, and limit fed 2.5 times maintenance for a metabolism study consisting of a 6-d adaptation period, followed by 72-h of urine and fecal collections. On d 12, pigs were necropsied, and ileal, cecal, and colonic digesta were collected for immediate short-chain fatty acid (SCFA) analysis. The pH of ileal and cecal digesta were also collected. Data were analyzed as a linear mixed model with treatment as a fixed effect, replicate as a random effect, and initial BW as a covariate where appropriate using PROC MIXED in SAS 9.4. The pH of both ileal (P = 0.478) and cecal (P = 0.874) digesta did not differ among treatments. Relative to SP, pigs fed SP+FIB and SBM had a 97.8% and 63.4% increase in acetate production, respectively (P = 0.012). Similarly, pigs fed SP+FIB and SBM had increased total SCFA concentration in the ileum (P = 0.016), but there was no difference among treatments for propionate or butyrate production (P &amp;gt; 0.05). The molar proportion of butyrate was increased in the cecum in pigs fed SBMC and SP+FIB (P &amp;lt; 0.01), which increased the total concentration (mM/g) of SCFA in the cecal digesta (P &amp;lt; 0.05). The SP+FIB treatment had increased concentration (mM/g) and molar proportion of butyrate produced in the colon (P &amp;lt; 0.01). While pigs fed SBMC and SP had increased molar proportion of propionate in the colon (P &amp;lt; 0.05), total colonic SCFA concentration did not differ (P &amp;gt; 0.05). Collectively, SBM and its fiber can modulate SCFA composition and production in nursery pigs, and this may be related to an increase in fermentable substrates available to the microbiome.

90 Microbiome-Derived Bioactive Molecules to Reduce Enteric Methane Emissions

Abstract Microorganisms are pivotal for the development, health, and productivity of livestock. In adult ruminants, the microbiota colonizing the rumen is essential for efficient depolymerization of indigestible carbohydrates from plant biomass and their conversion into microbial protein and fermentation end-products that are used by the host for growth. In the last decades, next-generation sequencing and omics technologies provided unparalleled insights into the composition, structure, and function of the gastrointestinal (GI) tract microbiome of ruminants and helped improve our understanding of relationships between the rumen microbiota with cattle performance (efficiency) traits, as well as health and disease and greenhouse gas emissions. The ecological interactions between microbes within the rumen ecosystem are complex and involve, among others, cross-feeding, predation, parasitism, antagonism, and competition for novel (empty) niches and available resources. These diverse associations of ecological traits across distinct microbial populations that coexist in the same ecosystem represent a goldmine for the discovery of novel bioactive molecules, including compounds with potential to modulate rumen fermentation and inhibit methane emissions from enteric fermentation. These effects often result from metabolic shifts in the rumen fermentation that lead to increased production of propionate, but can also be caused by direct inhibition of methanogenic archaea or through a reduction in the production of substrates for methanogenesis. Culture-independent approaches based on genome mining and functional metagenomics demonstrated that the rumen is an underexplored resource for bioactive molecules, such as antimicrobial peptides, non-ribosomal peptides, polyketides, and secondary metabolites involved in intercellular (microbe-microbe) communication. Rumen metatranscriptomic data indicate that the expression of genes potentially encoding some of these molecules is increased during the colonization of plant biomass that enters the rumen. Nonetheless, some representatives of key taxa from the core rumen microbiome cannot be found in culture collections, which is critical to validate phenotypic predictions from genomic and metagenomic data and obtain ecological insights about the interplay between individual microbial populations in the microbiome. Culturomic technologies and high-throughput identification and characterization of microbial species that colonize the rumen could contribute to building a unique biotechnological resource that can be explored for sourcing novel bioactive compounds with anti-methanogenic activity and developing fermentation products that could reduce rumen methanogenesis while improving the health status and productivity of cattle.

Effect of inoculum source, electron donors, and substrates on medium-chain fatty acid production from palm oil mill effluent

Selecting an appropriate inoculum source and electron donor for chain elongation is crucial to optimizing medium-chain fatty acid (MCFA) production from organic waste. The investigation examined the impact of various factors, including inoculum source, electron donors, and substrate composition, on MCFA production from palm oil mill effluent (POME). The substrate containing a mixture of ethanol, lactic acid, and acetic acid exhibited the highest MCFA production, reaching 0.4–0.5 g-COD/L. Among the cultures tested, the compost (CP)-enriched culture demonstrated the highest MCFA production (0.5 g-COD/L) and was characterized by the dominance of Sporanaerobacter sp., Clostridium sp., and Oscillibacter sp. The mesophilic condition (35 °C) has higher MCFA production than the thermophilic condition (55 °C), with the mesophilic system favoring caproic acid, heptanoic acid, and caprylic acid, while the thermophilic was more suitable for propionic acid production. The highest MCFA yield obtained from POME was 0.2 g-COD/g-COD, with a selectivity of 13.6 % for MCFA production. Lactobacillus sp., Caproiciproducens sp., and Clostridium sp. were dominant microbial species and played important roles in specific MCFA production. These findings provide valuable insights for optimizing MCFA production processes from POME and highlight the importance of selecting appropriate conditions and microbial communities to enhance MCFA yields.

Characteristics of the Gut Microbiota in Young Adults with Autism Spectrum Disorder.

Although the characteristics of the gut microbiota of children with autism spectrum disorder (ASD) have been well studied, those of young adults with ASD have seldom been reported. Using 16S rRNA gene sequencing, we characterized the gut microbiota of 19 young adults with ASD and compared them with that of 19 healthy adults. A random forest prediction model was used to distinguish between the two groups at the genus level. The abundance levels of one phylum, seven families, and 18 genera in adults with ASD were significantly different from those of controls. The genus Phascolarctobacterium was significantly enriched in adults with ASD, which might elicit ASD-like behavior through production of propionate. In addition, a random forest model identified 15 genera that could distinguish adults with ASD from healthy controls with areas under the receiver operating curve of 92.86%, and ten of them were biomarkers identified by LEfSe. Our results identified specific gut bacteria associated with ASD, and the successful application of certain genera in the prediction model further supports the association between gut microbiota and ASD.

Impact of ultrasound processing of açai juice containing complex carbohydrates in human intestinal microbiota composition and metabolite production

The present study evaluated the impact of high-intensity ultrasound processing of potentially prebiotic açai juice containing complex carbohydrates (dextran and oligosaccharides) on human gut microbiota after in vitro colonic fermentation. The juice was subjected to an in vitro simulated digestion and human fecal fermentation. HPLC quantified the metabolites produced during fecal fermentation, and the 16 S rRNA sequencing evaluated the microbiota change. The gluco-oligosaccharides and dextran were resistant to in vitro digestion and promoted the fecal microbiota production of short-chain fatty acids (SCFAs). The sonicated juice markedly increased propionic and butyric acid production, reaching 11 g/L and 4 g/L, respectively. The potentially prebiotic açai juice improved the richness (25%) and diversity (22%) of the fecal microbiota, and the ultrasound processing increased richness (12%) compared to non-sonicated juice, which may contribute to overall host health. The study demonstrated that açai juice containing gluco-oligosaccharides and dextran has a potential prebiotic effect. Incorporating this juice into the diet might promote gut-beneficial bacterial growth, improving the gut microbiota and the health-promoting metabolites.

In vitro study of potential prebiotic properties of monovarietal extra virgin olive oils

Olive oil, essential ingredient of the Mediterranean diet, is attracting a growing interest due to increasing evidence on its beneficial effects on human health. This study investigated whether extra virgin olive oil (EVOO) possess prebiotic properties. Twenty different monovarietal EVOO samples from 5 Marche region cultivars (Italy) were studied. The prebiotic activity of EVOOs was assessed monitoring the selective stimulation of gut bacterial species and the short chain fatty acids (SCFAs) production, using an in vitro fermentation system. All EVOOs selectively stimulated Lactobacillus spp., with a stronger activity than that observed in the inulin fermentation (positive control). Also, the bifidobacteria population increased; this bifidogenic stimulation was of EVOOs from Raggia cultivar. SCFAs appeared significantly higher after 24 h in all EVOO fermentations than in the control. Acetic and propionic acids production was particularly stimulated. Overall, most of the investigated EVOOs had a potential prebiotic activity, similar or stronger than inulin.

The oxidoreductase activity of Rnf balances redox cofactors during fermentation of glucose to propionate in Prevotella

Propionate is a microbial metabolite formed in the gastrointestinal tract, and it affects host physiology as a source of energy and signaling molecule. Despite the importance of propionate, the biochemical pathways responsible for its formation are not clear in all microbes. For the succinate pathway used during fermentation, a key enzyme appears to be missing—one that oxidizes ferredoxin and reduces NAD. Here we show that Rnf [ferredoxin—NAD+ oxidoreductase (Na+-transporting)] is this key enzyme in two abundant bacteria of the rumen (Prevotella brevis and Prevotella ruminicola). We found these bacteria form propionate, succinate, and acetate with the classic succinate pathway. Without ferredoxin:NAD+ oxidoreductase, redox cofactors would be unbalanced; it would produce almost equal excess amounts of reduced ferredoxin and oxidized NAD. By combining growth experiments, genomics, proteomics, and enzyme assays, we point to the possibility that these bacteria solve this problem by oxidizing ferredoxin and reducing NAD with Rnf [ferredoxin—NAD+ oxidoreductase (Na+-transporting)]. Genomic and phenotypic data suggest many bacteria may use Rnf similarly. This work shows the ferredoxin:NAD+ oxidoreductase activity of Rnf is important to propionate formation in Prevotella species and other bacteria from the environment, and it provides fundamental knowledge for manipulating fermentative propionate production.

Enzymatic production of cello-oligosaccharides with potential human prebiotic activity and release of polyphenols from grape marc

Grape marc, the main winemaking byproduct, is an excellent source of bioactive polyphenols, such as anthocyanins, resveratrol and quercetin. An enzyme-catalysed treatment of marc was developed using endo-1,4-β-d-glucanase to release polyphenol O-glucosides and simultaneously generate the optimal concentration of water-soluble cello-oligosaccharides (COS), including cellopentaose, cellotriose, and cellobiose from the marc matrix. The prebiotic properties of marc hydrolysate rich in COS was assessed using human probiotic monocultures of Lactobacillus spp. and Bifidobacterium spp. strains, and invitro human faecal fermentation. The COS-rich hydrolysate showed excellent prebiotic effect in both studies, successfully supporting the growth of beneficial probiotic strains, and was highly fermentable by faecal microbiota producing gas and short chain fatty acids. Acetate and propionate production were the highest when faecal bacteria fermented COS-rich solution compared with standard substrates. For the first time, COS was shown to be fermented by faecal microbiota, demonstrating the potential benefits of valorised grape marc.

Effect of grape pomace supplement on growth performance, gastrointestinal microbiota, and methane production in Tan lambs.

Grape pomace (GP), a by-product in wine production, is nutritious and can be used as a feed ingredient for ruminants; however, its role in shaping sheep gastrointestinal tract (GIT) microbiota is unclear. We conducted a controlled trial using a randomized block design with 10 Tan lambs fed a control diet (CD) and 10 Tan lambs fed a pelleted diet containing 8% GP (dry matter basis) for 46 days. Rumen, jejunum, cecum, and colon bacterial and archaeal composition were identified by 16S rRNA gene sequencing. Dry matter intake (DMI) was greater (p < 0.05) in the GP than CD group; however, there was no difference in average daily gain (ADG, p < 0.05) and feed conversion ratio (FCR, p < 0.05) between the two groups. The GP group had a greater abundance of Prevotella 1 and Prevotella 7 in the rumen; of Sharpe, Ruminococcaceae 2, and [Ruminococcus] gauvreauii group in the jejunum; of Ruminococcaceae UCG-014 and Romboutsia in the cecum, and Prevotella UCG-001 in the colon; but lesser Rikenellaceae RC9 gut group in the rumen and cecum, and Ruminococcaceae UCG-005 and Ruminococcaceae UCG-010 in the colon than the CD group. The pathways of carbohydrate metabolism, such as L-rhamnose degradation in the rumen, starch and glycogen degradation in the jejunum, galactose degradation in the cecum, and mixed acid fermentation and mannan degradation in the colon were up-graded; whereas, the pathways of tricarboxylic acid (TCA) cycle VIII, and pyruvate fermentation to acetone in the rumen and colon were down-graded with GP. The archaeal incomplete reductive TCA cycle was enriched in the rumen, jejunum, and colon; whereas, the methanogenesis from H2 and CO2, the cofactors of methanogenesis, including coenzyme M, coenzyme B, and factor 420 biosynthesis were decreased in the colon. The study concluded that a diet including GP at 8% DM did not affect ADG or FCR in Tan lambs. However, there were some potential benefits, such as enhancing propionate production by microbiota and pathways in the GIT, promoting B-vitamin production in the rumen, facilitating starch degradation and amino acid biosynthesis in the jejunum, and reducing methanogenesis in the colon.

Fibre-rich diet attenuates chemotherapy-related neuroinflammation in mice

The gastrointestinal microbiota has received increasing recognition as a key mediator of neurological conditions with neuroinflammatory features, through its production of the bioactive metabolites, short-chain fatty acids (SCFAs). Although neuroinflammation is a hallmark shared by the neuropsychological complications of chemotherapy (including cognitive impairment, fatigue and depression), the use of microbial-based therapeutics has not previously been studied in this setting. Therefore, we aimed to investigate the effect of a high fibre diet known to modulate the microbiota, and its associated metabolome, on neuroinflammation caused by the common chemotherapeutic agent 5-fluorouracil (5-FU). Twenty-four female C57Bl/6 mice were treated with 5-FU (400 mg/kg, intraperitoneal, i.p.) or vehicle control, with or without a high fibre diet (constituting amylose starch; 4.7 % crude fibre content), given one week prior to 5-FU and until study completion (16 days after 5-FU). Faecal pellets were collected longitudinally for 16S rRNA gene sequencing and terminal SCFA concentrations of the caecal contents were quantified using gas chromatography-mass spectrometry (GC–MS). Neuroinflammation was determined by immunofluorescent analysis of astrocyte density (GFAP). The high fibre diet significantly altered gut microbiota composition, increasing the abundance of Bacteroidaceae and Akkermansiaceae (p < 0.0001 and p = 0.0179) whilst increasing the production of propionate (p = 0.0097). In the context of 5-FU, the diet reduced GFAP expression in the CA1 region of the hippocampus (p < 0.0001) as well as the midbrain (p = 0.0216). Astrocyte density negatively correlated with propionate concentrations and the abundance of Bacteroidaceae and Akkermansiaceae, suggesting a relationship between neuroinflammatory and gastrointestinal markers in this model. This study provides the first evidence of the neuroprotective effects of fibre via dietary intake in alleviating the neuroimmune changes seen in response to systemically administered 5-FU, indicating that the microbiota-gut-brain axis is a targetable mediator to reduce the neurotoxic effects of chemotherapy treatment.

Fucose modifies short chain fatty acid and H2S formation through alterations of microbial cross-feeding activities.

Algae are a rich but unexplored source of fibers with the potential to contribute to the next generation of prebiotics. The sulfated brown algae polysaccharide, fucoidan, is mainly composed of the deoxy-hexose L-fucose, which can be metabolized to 1,2-propanediol (1,2-PD) or lactate by gut microbes as precursors of propionate and butyrate. It was the aim of this study to investigate the impact of fucoidan on the fermentation capacity of the fecal microbiota and to compare to fucose. In batch fermentations of fecal microbiota collected from 17 donor samples, fucose promoted the production of propionate while no consistent effect was observed for commercial fucoidan and Fucus vesiculosus extract prepared in this study containing laminarin and fucoidan. H2S production was detected under all tested conditions, and levels were significantly lower in the presence of fucose in a dose-dependent manner. The addition of high fucose levels led to higher relative abundance of microbial 1,2-PD and lactate cross-feeders. Our results highlight that fucose and not fucoidan addition impacted fermentation capacity and increased the proportions of propionate and butyrate, which allows for precise modulation of intestinal microbiota activity.

Optimising organic composition of feedstock to improve microbial dynamics and symbiosis to advance solid-state anaerobic co-digestion of sewage sludge and organic waste

This study provided new insight to the underlying mechanisms, by which organic compositions, including protein, fat, degradable carbohydrates and lignocellulose, regulate the performance of solid-state anaerobic digestion (SSAD) for synergistic treatment of organic wastes. Results show that the feedstock with a balanced composition of protein, fat, degradable carbohydrates and lignocellulose could maintain SSAD homeostasis to enhance methane (CH4) production by 14–487%. On the other hand, organic waste with a high content of degradable carbohydrates and fat at 39 and 14%, respectively, showed an initially high CH4 production at the beginning but a lower overall CH4 production. This was because of the accumulation of volatile fatty acids (VFAs) and ammonium nitrogen (NH4+-N) at up to 17.3 and 7227.7 mg·L−1, respectively, leading to anaerobic activity inhibition. Microbial dynamic and modular network analyses indicated that the balanced feedstock secured stepwise biodegradation of different organic substances to reduce the relative abundance of hydrolytic bacteria (e.g. Rikenellaceae_RC9_gut_group and Tepidimicrobium), thus alleviating VFAs and NH4+-N stresses. In particular, fat in the balanced feedstock could not only enrich the phylum Firmicutes for macromolecular biodegradation and genes for VFAs production, but also inhibit relative oxidizers (e.g. Synergistes and Acinetobacter) to facilitate propionate and acetate production to strengthen acetotrophic methanogenesis for effective CH4 yield. Results in this study show that a balanced organic composition could regulate microbial dynamics and symbiosis to advance SSAD homeostasis and methanation in synergistic organic waste treatment.

Influence of pH, Heat Treatment of Inoculum, and Selenium Oxyanions on Concomitant Selenium Bioremediation and Volatile Fatty Acid Production from Food Waste.

Developing novel strategies to enhance volatile fatty acid (VFA) yield from abundant waste resources is imperative to improve the competitiveness of biobased VFAs over petrochemical-based VFAs. This study hypothesized to improve the VFA yield from food waste via three strategies, viz., pH adjustment (5 and 10), supplementation of selenium (Se) oxyanions, and heat treatment of the inoculum (at 85 °C for 1 h). The highest VFA yield of 0.516 g COD/g VS was achieved at alkaline pH, which was 45% higher than the maximum VFA production at acidic pH. Heat treatment resulted in VFA accumulation after day 10 upon alkaline pretreatment. Se oxyanions acted as chemical inhibitors to improve the VFA yield at pH 10 with non-heat-treated inoculum (NHT). Acetic and propionic acid production was dominant at alkaline pH (NHT); however, the VFA composition diversified under the other tested conditions. More than 95% Se removal was achieved on day 1 under all the conditions tested. However, the heat treatment was detrimental for selenate reduction, with less than 15% Se removal after 20 days. Biosynthesized Se nanoparticles were confirmed by transmission and scanning electron microscopy and and energy dispersive X-ray analyses. The heat treatment inhibited the presence of nonsporulating bacteria and methanogenic archaea (Methanobacteriaceae). High-throughput sequencing also revealed higher relative abundances of the bacterial families (such as Clostridiaceae, Bacteroidaceae, and Prevotellaceae) that are capable of VFA production and/or selenium reduction.

Combined effects of vitamin B12 and fumarate on rumen propionate production and methanogenesis in dairy cow in vitro

AbstractThis study explored the combined effects of vitamin B12 and fumarate supplementation on methane (CH4) emission and propionate synthesis in dairy cows through simulated rumen fermentation in vitro. The experimental animals were 3 cows with an average milk yield of 23 ± 2.8 kg/d, a body weight of 618 ± 100 kg, and a parity of 3 ± 1 that were selected as rumen fluid donors. The TMR diet fed to cows is a fermentation substrate. Experiments adopted 2 × 2 factorial design, including control group, vitamin group (1 mg/g DM vitamin B12), fumarate group (100 mg/g DM), and combined addition group (1 mg/g DM vitamin B12 and 100 mg/g DM). All treatments had no effect on the dry matter degradation (DMD). Both vitamin B12 and fumarate reduced CH4 emission, increased the propionate concentration, and reduced the acetate/propionate ratio without any observed interaction. Vitamin B12 made Prevotella and Prevotellaceae_ UCG‐003 increase in quantity, and fumarate increased the abundance of Succinivibrionaceae_UCG‐002 and Selenomonas, both of which are propionate‐producing bacteria. At the species level, the supplementation of vitamin B12 and fumarate slightly changed the abundance of some strains, but it was not statistically significant. Shifts in the abundance of propionate‐producing bacteria and methanogenic archaea species suggest an increase in propionate production and a decrease in CH4 emission. In conclusion, the addition of vitamin B12 and fumarate changed the fermentation mode of the rumen and reduced the emission of CH4 by affecting the structure of the rumen microbial community, but no obvious interaction was found between the two.