Elevated Propionate Research Articles

Effects of Bacillus subtilis addition to milk replacer on growth performance, nutrient digestibility, intestinal microbiota, and short-chain fatty acid concentration of Hu lambs

We aimed to investigate the effects of adding Bacillus subtilis to milk replacers on the incidence of diarrhea, growth performance, intestinal microbiota composition, and short-chain fatty acid (SCFA) production in newborn Hu lambs. Thirty newborn lambs with similar genetic backgrounds and initial body weights were selected and nursed by their dams for 4 days before transitioning to a milk replacer. At age 7 days, the lambs were randomly assigned to two experimental groups of 15 lambs each: CON (basic milk replacer feeding) and BS (basic milk replacer feeding supplemented with 0.2% B. subtilis). At age 28 days, eight lambs in each group were randomly euthanized, and their colonic and cecal contents were collected for microbiological and SCFA analyses. The lambs were monitored daily to determine the incidence of diarrhea. The BS group showed significantly increased average daily feed intake and gain and significantly reduced incidence of diarrhea. Furthermore, dry matter digestibility and crude protein and ether extract content increased in the BS group compared with those in the CON group. Increased acetate and total SCFA concentrations were noted in the colon and cecum, with elevated propionate levels specifically in the cecum. Microbiota analysis revealed that B. subtilis supplementation enhanced microbial diversity and beneficially modulated bacterial communities. Potentially harmful bacteria showed significantly decreased abundance in the colon (Campylobacterota by 11.09% and Fusobacteriota by 2.98%), whereas beneficial bacteria exhibited increased abundance (Firmicutes by 8.9%, Actinobacteriota by 3.59%, Lactobacillus by 5.92%, and Bifidobacterium by 3.18%). Similar trends were observed in the cecum, with decreases in Campylobacterota (4.82%) and Fusobacteriota (3.12%) and increases in Bacteroidota (4.11%), Lactobacillus (3.75%), and Prevotella (3.59%). These findings indicate that adding 0.2% B. subtilis to the milk replacer is an effective approach for enhancing lamb growth performance, maintaining intestinal health, and improving the intestinal microbiota.

Changes in Human Colonic Microbiota Promoted by Synbiotic Açai Juice Composed of Gluco-Oligosaccharides, Dextran, and Bifidobacterium breve NRRL B-41408.

The present study evaluates the effects of açai juice containing gluco-oligosaccharides and dextran, fermented by Bifidobacterium breve NRRL B-41408 (synbiotic juice), on the human fecal microbiota. The juice is subjected to simulated digestion and fecal fermentation after production and 42 days of refrigerated storage. High throughput 16S rRNA sequencing and HPLC are used to identify the bacterial cells and metabolites. The results show that the viability of B. breve is stable during the refrigerated storage, indicating that the metabolism is maintained even under low temperatures and pH. Furthermore, gluco-oligosaccharides and dextran prove to be resistant to gastrointestinal conditions and are quickly consumed during fecal fermentation. The synbiotic açai juice enhances the microbial diversity and stimulates the production of short-chain fatty acids (SCFA), including acetate, propionate, and isobutyrate. Elevated propionate levels are directly associated with an increased abundance of Bacteroides thetaiotaomicron, Bacteroides uniformis, Bacteroides xylanisolvens, Bacteroides dorei, Bacteroides stercoris, and Bacteroides massiliensis after 48 h of fermentation. This highlights the potential of synbiotic açai juice as a functional beverage, supported by the significant increase in microbial diversity reflected in the Shannon and Simpson's diversity indexes (Shannon = 116.6%, 117.2%, 125.15%, and 116.02%; Simpson's = 151.86%, 177.22%, 152.5%, and 163.73%).

Comparative Analysis of Rumen Fermentation and Microbial Communities in Yaks of Different Ages

Background: This study investigates the differences in rumen fermentation parameters and microbial communities in yaks aged 3 (MarG), 4 (AprG) and 5 months (MayG). As crucial livestock on the Qinghai-Tibet Plateau, optimizing yak health and productivity relies on understanding their rumen microbial structure and fermentation efficiency. These findings provide insights into their adaptation to the plateau environment and support strategies for improving livestock management. Methods: The study analyzed rumen fermentation parameters (NH3-N, acetate, propionate, isobutyrate, butyrate, valerate) and microbial composition in three age groups of yak calves. Microbial richness and composition were assessed, with network and correlation analyses identifying key microbial phyla associated with fermentation. Functional predictions explored gene abundances related to transcription, viral infection, cancer types and the immune system across the groups. Result: NH3-N and acetate levels were significantly higher in the MarG group compared to AprG and MayG (p less than 0.05), while MayG showed elevated propionate, isobutyrate, butyrate and valerate levels (p less than 0.05). Microbial composition varied, with Firmicutes and Actinobacteriota dominating MarG, Christensenellaceae and Oscillospiraceae in AprG and Desulfobacterota in MayG. Network analysis identified Proteobacteria as central in MarG, Firmicutes in AprG and both in MayG, forming the most complex network. UCG-005 showed strong positive correlations with all fermentation parameters. Functional predictions indicated higher cell motility in MarG and more immune-related genes in MayG.

Mulberry polyphenols restored both small and large intestinal microflora in db/db mice, potentially alleviating type 2 diabetes.

Polyphenols in mulberry fruit have potential anti-diabetic effects by targeting the gut microbiota. This study investigated how mulberry polyphenols (MPs) influence the microbiota of the small and large intestines and their effects on type 2 diabetes symptoms. The results showed lower microbiota densities in the small intestine. MP treatments improved microbiota richness and diversity in both intestines, similar to metformin. In particular, at a 400 mg kg-1 dose, mulberry polyphenols decreased Firmicutes, Lactobacillus, and Bacilli, while increasing Bacteroidetes, leading to elevated propionate and butyrate levels. Less abundant small intestinal microbiota, like Enterobacterales, Mycoplasmatales, Enterobacteriaceae, and Ureaplasma, were involved in regulating blood glucose and insulin levels. Functional analysis suggested that mulberry polyphenols reshaped the small intestinal microbiota to influence blood glucose balance via unknown pathways, while in the large intestine, they primarily affected blood glucose through carbohydrate transport and metabolism. Based on their ability to regulate the composition of intestinal flora, MPs likely improved glucose homeostasis by enhancing glucose utilization, supporting pancreatic tissue health, and increasing serum antioxidant capacity. However, the specific mechanisms underlying this potential are yet to be fully explored. This study provides new insights into the influence of MPs on remodeling the microbiota residing in both the small and large intestines, which thereby may contribute to the improvement of the pathophysiology of type 2 diabetes.

Isomalt attenuates hepatic steatosis in rats via modulating gut microbiota and its metabolic function

Growing studies have shown the preventive effects of isomalt against metabolic diseases, nevertheless, its efficacy and action mechanisms on nonalcoholic fatty liver disease (NAFLD) remain unknown. Herein, isomalt supplementation significantly attenuated the high-sucrose diet-induced hepatic steatosis. Mechanically, dietary isomalt restored hepatic de novo lipogenesis dysfunction and intestinal epithelial integrity. Moreover, isomalt consumption regulated gut microbiota composition, including improving abundance of probiotic Akkermansia, but suppressing pathogens Acinetobacter and Corynebacterium_1. Quantification analyses of short-chain fatty acids showed that isomalt reduced faecal acetate concentrations, whereas elevated propionate and butyrate in hepatic steatosis. Additionally, targeted metabolomics profiling of tryptophan metabolism showed that isomalt increased faecal levels of 5-hydroxytryptophan, indole-3-carboxaldehyde and kynurenic acid, but reduced concentrations of 5-hydroxyindoleacetic acid and xanthurenic acid in rats. Thereby, our data demonstrate that dietary isomalt attenuates hepatic steatosis possibly via modulation of gut microbiota and its metabolic function, which provides new insights into preventing and treating NAFLD in future.

Comparative effects of medium-chain fatty acids or phytobiotics-based feed additives on performance, caecum microbiota, volatile fatty acid production and intestinal morphology of broilers.

Antibiotic growth promoters have been utilized in broiler nutrition to alleviate the negative effects of the pathogenic microbes to promote performance. However, after the prohibition of antibiotics because of the increasing disclosure related to public health issues, various products have been developed as alternatives. This study was carried out to determine the effects of medium-chain fatty acids (MCFAs) or phytobiotics (essential oils [EOs] and alkaloids [ALKs]), blended feed additives on the growth performance, jejunum histomorphology, and cecal microbiota of broiler chickens. A total of 765 male Ross 308 chicks were randomly distributed into 5 experimental groups, each having 9 replicates with 17 chicks. The experimental procedures were as follows: a control group without supplementation (T1); control group+ MCFAs and EOs blend (T2); control group+ different EOs blend (T3); control group+ ALK sanguinarine (T4); and control group+ EOs and ALK piperine mixture (T5). The results showed that, broilers fed with MCFAs blended with EOs had significantly greater body weight gain during overall period in comparision to the control and T3 groups. Further, only MCFAs blended with EOs group significantly improved jejnum morphology in comparison with the control group (p≤0.05). Besides, the MCFAs blended with EOs group significantly elevated propionate, acetate and butyrate concentration, and decreased the concentration of branch chain fatty acids in caecum (p≤0.05). The results indicated that, the combination of MCFAs and EOs seems to have improvement effects and could be preferred as an efficient feed additive in broiler production.

Patterns of syntrophic interactions in methanogenic conversion of propionate.

Methanogenesis is central to anaerobic digestion processes. The conversion of propionate as a key intermediate for methanogenesis requires syntrophic interactions between bacterial and archaeal partners. In this study, a series of methanogenic enrichments with propionate as the sole substrate were developed to identify microbial populations specifically involved in syntrophic propionate conversion. These rigorously controlled propionate enrichments exhibited functional stability with consistent propionate conversion and methane production; yet, the methanogenic microbial communities experienced substantial temporal dynamics, which has important implications on the understanding of mechanisms involved in microbial community assembly in anaerobic digestion. Syntrophobacter was identified as the most abundant and consistent bacterial partner in syntrophic propionate conversion regardless of the origin of the source culture, the concentration of propionate, or the temporal dynamics of the culture. In contrast, the methanogen partners involved in syntrophic propionate conversion lacked consistency, as the dominant methanogens varied as a function of process condition and temporal dynamics. Methanoculleus populations were specifically enriched as the syntrophic partner at inhibitory levels of propionate, likely due to the ability to function under unfavorable environmental conditions. Syntrophic propionate conversion was carried out exclusively via transformation of propionate into acetate and hydrogen in enrichments established in this study. Microbial populations highly tolerant of elevated propionate, represented by Syntrophobacter and Methanoculleus, are of great significance in understanding methanogenic activities during process perturbations when propionate accumulation is frequently encountered. Key points • Syntrophobacter was the most consistent bacterial partner in propionate metabolism. • Diverse hydrogenotrophic methanogen populations could serve as syntrophic partners. • Methanoculleus emerged as a methanogen partner tolerant of elevated propionate.

Enteric Methane Emissions and Rumen Fermentation Profile Treated by Dietary Chitosan: A Meta-Analysis of In Vitro Experiments

Chitosan is a natural compound obtained from deacetylation of chitin, which is a biopolymer present in the exoskeleton of crustaceans such as crabs and shrimp. The present study aimed to perform a meta-analysis from published studies regarding the effects of chitosan on methane emission and rumen fermentation profile of in vitro batch culture experiments. A total of 41 studies from 12 articles were integrated into a database. Parameters included were gas production, methane emission, rumen fermentation characteristics, microbial population, nutrient digestibility, and fatty acid profile. Data were analyzed according to mixed model methodology in which different studies were treated as random effects and chitosan addition levels were treated as fixed effects. Results showed that chitosan addition was able to reduce enteric methane emissions (p<0.001). Such methane decrease was accompanied by a decline in the protozoa population (p<0.05) and a tendency of methanogen reduction (p<0.1). The increasing chitosan level was associated with a decrease in total VFA and ammonia concentrations (both at p<0.001). Chitosan addition decreased acetate proportion (p<0.001) while elevated propionate proportion (p<0.001). Chitosan was associated with an increase of dry matter digestibility, crude protein digestibility, and neutral detergent fiber digestibility (p<0.001). Chitosan increased concentrations of C18:3n3 (p<0.05), conjugated linoleic acid (p<0.01) and polyunsaturated fatty acids (p<0.01) while decreased concentration of saturated fatty acids (p<0.001). It can be concluded that chitosan addition can mitigate enteric methane emission and alters rumen fermentation profiles in a favorable direction.

Elevated Gut Microbiome-Derived Propionate Levels Are Associated With Reduced Sterile Lung Inflammation and Bacterial Immunity in Mice

Short-chain fatty acids (SCFA) are important dietary and microbiome metabolites that can have roles in gut immunity as well as further afield. We previously observed that gut microbiome alteration via antibiotics led to attenuated lung inflammatory responses. The rationale for this study was to identify gut microbiome factors that regulate lung immune homeostasis. We first investigated key factors within mouse colonic lumen filtrates (CLF) which could elicit direct inflammatory effects in vitro. We identified lipopolysaccharide (LPS) and SCFAs as key CLF ingredients whose levels and inflammatory capacity changed after antibiotic exposure in mice. Specifically, the SCFA propionate appeared to be a key regulator of LPS responses in vitro. Elevated propionate: acetate ratios, as seen in CLF after antibiotic exposure, strongly blunted inflammatory responses in vitro. In vivo, exposure of lungs to high dose propionate, to mimic how prior antibiotic exposure changed SCFA levels, resulted in diminished immune containment of Staphylococcus aureus pneumonia. Finally, we discovered an enrichment of propionate-producing gut bacteria in mice with reduced lung inflammation following lung ischemia reperfusion injury in vivo. Overall, our data show that propionate levels can distinctly modulate lung immune responses in vitro and in vivo and that gut microbiome increased production of propionate is associated with reduced lung inflammation.

Soluble xyloglucan generates bigger bacterial community shifts than pectic polymers during in vitro fecal fermentation

Xyloglucans and pectic polymers can be obtained from a variety of plants ubiquitous in the human diet, however, their fermentability in the colon and consequent nutritional benefits are poorly understood. Here, we evaluated metabolite profiles and bacterial shifts during in vitro fecal fermentations of two isolated pectic polymers and a xyloglucan. Depending on their chemical structure, pectic polymers were more acetogenic or propiogenic. Xyloglucan fermentation also resulted in elevated propionate if compared to FOS. Bacteroides plebeius, B. uniformis, Parabacteroides distasonis and bacterial groups such as Blautia, Lachnospira, Clostridiales and Lachnospiraceae, presented distinct abundances on each dietary fiber ferment. PCA and heat map analysis showed that major microbiota shifts occurred during xyloglucan fermentation, but not pectin fermentation. These data suggest that uncommon carbohydrate structures (i.e. isolated, soluble xyloglucan) in the diet hold the potential to generate larger shifts in microbiota communities than commonly consumed fibers (i.e. pectins).

Elevated propionate and butyrate in fecal ferments of hydrolysates generated by oxalic acid treatment of corn bran arabinoxylan.

Previous work in our laboratory showed that alkali-solubilized corn arabinoxylan (CAX) has a slow initial, but later complete, in vitro human fecal fermentation. CAX and a moderately high molecular weight hydrolysate (CH) were propiogenic, and produced low levels of butyrate. Here, we show that oxalic acid-generated hydrolysates from CAX, which include a large xylooligosaccharide, and free arabinose fractions, increased short chain fatty acid (SCFA) production, which included relatively high levels of both propionate and butyrate, an unusual SCFA combination. Hydrolytic degradation of CAX by acid hydrolysis (0.05 M oxalic acid at 100 °C for 2 h) and subsequent graded ethanol precipitations were used to obtain mixtures with different molecular weight ranges. Ethanol-precipitated fractions (F 0-65%, F 65-75%, F 75-85%) were mostly lower than 100 kDa and F > 85% was composed of monosaccharides and oligosaccharides of DP 2-8. Oxalic acid treatment caused the removal of all single arabinose unit branch chains and some di/trisaccharide branch chains, producing lightly substituted xylan backbone fragments, most of which were in the oligosaccharide (DP < 10) size range. In vitro human fecal fermentation analyses showed all oxalic acid-hydrolysate fractions were slower fermenting than fructooligosaccharides (FOS), but produced similar or higher amounts of total SCFAs. Butyrate production in two hydrolyzate fractions was double that of CH, while propionate levels remained relatively high.

Impact of Dietary Fiber Fermentation from Cereal Grains on Metabolite Production by the Fecal Microbiota from Normal Weight and Obese Individuals

Gut bacteria may influence obesity through the metabolites produced by dietary fiber fermentation (mainly, short-chain fatty acids [SCFA]). Five cereal grain samples (wheat, rye, maize [corn], rice, and oats) were subjected to in vitro digestion and fermentation using fecal samples from 10 obese and nine normal weight people. No significant differences in total SCFA production between the normal weight and obese groups were observed [279 (12) vs. 280 (12), mean (standard error), respectively; P=.935]. However, the obese microbiota resulted in elevated propionate production compared with that of normal weight [24.8(2.2) vs. 17.8(1.9), respectively; P=.008]. Rye appeared to be particularly beneficial among grain samples due to the lowest propionate production and highest butyrate production during fermentation. These data suggest that the dietary fibers from cereal grains affect bacterial metabolism differently in obese and normal weight classes and that certain grains may be particularly beneficial for promoting gut health in obese states.

Antibiotics in the human food chain: Establishing no effect levels of tetracycline, neomycin, and erythromycin using a chemostat model of the human colonic microflora

A chemostat model of the healthy human large bowel ecosystem was used to establish no effect levels for tetracycline, neomycin, and erythromycin. For each compound, the equivalent to four oral doses (0, 1.5, 15, and 150 mg/60 kg person/d) was studied. Concentrations of the test compounds in the chemostat medium were intended to simulate fecal levels that might be expected following consumption of food containing antibiotic residue and were based on published oral doses and fecal levels. We monitored the following parameters: short chain fatty acids, bile acids, sulfate reduction, azoreductase and nitroreductase activities, β-glucosidase and β-glucuronidase activities, a range of bacterial counts and, lastly, the susceptibility among sentinel bacteria to each test compound. Neomycin and erythromycin reduced bile acid metabolism. Neomycin elevated propionate levels and caused a marginal diminution in azoreductase activity. Based on our results, the no observed effect level (NOEL) of both tetracycline and erythromycin was 15 mg/60 kg person/d. The NOEL for neomycin was 1.5 mg/60 kg person/d.

Staging of anaerobic processes for reduction of chronically high concentrations of propionic acid

The objective of this research was the reduction of chronic elevated propionate from a bench‐scale, anaerobic completely stirred tank reactor (CSTR) without biomass recycle treating synthetic molasses wastewater. Pretreatment and posttreatment alternatives were specifically examined using a high–food‐to‐microorganism (F/M) contact chamber as the preliminary operation unit in one case and an upflow anaerobic sludge blanket (UASB) reactor as the posttreatment unit in the second case. The high‐F/M contact reactor unit, operated before the main reactor, was a two‐stage (not a two‐phase) configuration. After the feed contacted biomass that was recycled from the main reactor for a period of 1 day in a high‐F/M contact reactor, the entire contents of the high‐F/M contact reactor were transferred back to the main reactor. This brief contact operation resulted in a dramatic decrease in propionate concentrations in the effluent of the main reactor, which had been producing consistently high concentrations for approximately 4 months. After incorporation of the high‐F/M contact reactor in the preliminary treatment step, the propionic acid concentration dropped significantly, from 1 050 mg/L to 300 mg/L. The results of this investigation showed that the contact time and F/M ratio in the high‐F/M reactor were critical parameters in determining the efficacy of the two‐stage configuration. In the second part of the study, the effluent from the main reactor (not incorporating a precontact reactor) was subjected to posttreatment by a UASB reactor filled with granular biomass. After an acclimation period of approximately 1 month, which provided a hydraulic retention time of 1 day in the UASB unit, the concentration of approximately 1 050 mg/L of propionic acid in the main reactor effluent fell to less than the quantification limit of 20 mg/L in the effluent of the UASB posttreatment unit. The overall success of both portions of the study seem to demonstrate the inappropriateness of using a one‐stage CSTR process configuration for anaerobic metabolism of propionate derived from carbohydrate wastewaters.

Blood metabolite and regulatory hormone concentrations and response to metabolic challenges during the infusion of mimosine and 2,3-dihydroxypyridine in alpine goats.

Sixteen Alpine wethers (average BW 35 +/- 2 kg) were used to evaluate the effect of continuous 48-h intravenous infusions of saline (CON), mimosine (MIM; 200 mg.kg.75.d-1), 2-hydroxy-3(1H)-pyridine (2,3-DHP; 200 mg.kg.75.d-1, or MIM+2,3-DHP (100 mg of MIM plus 100 mg of 2,3-DHP-kg.75.d-1) on hepatic function and selected blood metabolite and circulating hormone concentrations. Neither MIM nor 2,3-DHP affected plasma ammonia N, glucose, cortisol, or insulin concentrations over time (P > .10). Jugular plasma total protein concentration was greater in the MIM group (P < .07). Plasma triiodothyronine (P < .01) and thyroxine (P < .08) concentrations were higher in the goats receiving the MIM, 2,3-DHP, and MIM+2,3-DHP infusions than in the goats receiving the CON infusion. Plasma urea N concentration was decreased by MIM (P < .10) and MIM+2,3-DHP (P < .03) compared with the CON infusion. A Propionate Load Test was conducted at 24 to 28 h into the infusion to assess the toxins' effects on the liver's ability to increase circulating glucose concentrations in the presence of elevated propionate levels. The results indicated that neither 2,3-DHP nor MIM reduced the liver's ability to respond to a bolus dose of propionate (P > .10). Following a Urea Load Test, circulating ammonia N and glucose concentrations in the MIM, 2,3-DHP, and MIM+2,3-DHP treatments had lower peak values than that in the CON treatment (P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)