Hydrogen and formate production and utilisation in the rumen and the human colon

Kelly, William J.; Mackie, Roderick I.; Attwood, Graeme T.; Janssen, Peter H.; McAllister, Tim A.; Leahy, Sinead C.

doi:10.1186/s42523-022-00174-z

Cited by 28 publications

(19 citation statements)

References 64 publications

(84 reference statements)

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“…Species and strains of Erwinia are known to vary in the relative amounts of succinate, formate, lactate, acetate, 2,3 butanediol and ethanol that they produce [ 44 ]. No significant amounts of succinate, formate or lactate were found in the fermentations, though all three are capable of being converted to other products by gut microbes [ 47 , 48 ]. Alcohols were not measured.…”

Section: Resultsmentioning

confidence: 99%

Evaluating the efficacy of non-thermal microbial load reduction treatments of heat labile food components for in vitro fermentation experiments

Paff

Cockburn

2023

PLoS ONE

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Increasingly, in vitro simulated colon fermentations are being used as a pre-clinical step to assess the impacts of foods and drugs on the gut microbiota in a cost-effective manner. One challenge in such systems is that they are potentially susceptible to the influences of contaminating microbes in test materials. Simulated gastric and intestinal digestion can relieve some of these concerns, however, live microbes may remain that can confound analysis. Autoclave treatment of test materials is the surest way to eliminate these microbes but presents problems when using heat labile components such as resistant starch. In this study, liquid chemical sterilant alternatives to moist heat sterilization were explored for treating pulse flours for use during in vitro simulated colon fermentation. Key attributes considered in chemical selection were accessibility, impact on treated food components, and effectiveness of the treatments for reducing microbial load. Three chemicals were selected for evaluation, bleach, alcohol, and hydrogen peroxide, at varying concentrations. Flours chosen for testing were from green lentil, field pea, chickpea, or sprouted green lentil. All treatments significantly reduced microbial loads, though there were still detectable levels of microbes after alcohol treatments. Furthermore, in vitro simulated colon fermentations of the treated pulses showed minimal difference from the untreated control both in terms of microbial composition and short chain fatty acid production. Scanning electron microscopy showed minimal impact of sterilization treatments on the gross structure of the pulse flours. Together these results suggest that bleach and hydrogen peroxide treatments can be effective nonthermal treatments to eliminate contaminating microbes in pulse flours without causing significant damage to starch and other fermentable substrates. This is thus also a promising treatment method for other starchy food substrates, though further testing is required.

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Section: Resultsmentioning

confidence: 99%

Evaluating the efficacy of non-thermal microbial load reduction treatments of heat labile food components for in vitro fermentation experiments

Paff

Cockburn

2023

PLoS ONE

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“…The process of hydrogen sink is best described in ruminants. It is known that in the environment of the rumen, the methanogenic archaea dominate over the homoacetogens, especially at low concentrations of H 2 [ 2 , 19 ]. Only when methanogenesis is suppressed do acetogens take over methanogen’s place [ 18 ].…”

Section: Discussionmentioning

confidence: 99%

“…Hydrogen—a fermentation byproduct—when accumulated, has the ability to inhibit the regeneration of electron carriers by bacterial fermenters, and therefore adversely inhibits fermentation. The problem of hydrogen buildup appears to be solved by the process of hydrogen sink carried out by certain groups of intestinal microorganisms [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

Microorganisms Involved in Hydrogen Sink in the Gastrointestinal Tract of Chickens

Cisek

Dolka

Bąk

et al. 2023

IJMS

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Hydrogen sink is a beneficial process, which has never been properly examined in chickens. Therefore, the aim of this study was to assess the quantity and quality of microbiota involved in hydrogen uptake with the use of real-time PCR and metagenome sequencing. Analyses were carried out in 50 free-range chickens, 50 commercial broilers, and 54 experimental chickens isolated from external factors. The median values of acetogens, methanogens, sulfate-reducing bacteria (SRB), and [NiFe]-hydrogenase utilizers measured in the cecum were approx. 7.6, 0, 0, and 3.2 log10/gram of wet weight, respectively. For the excreta samples, these values were 5.9, 4.8, 4, and 3 log10/gram of wet weight, respectively. Our results showed that the acetogens were dominant over the other tested groups of hydrogen consumers. The quantities of methanogens, SRB, and the [NiFe]-hydrogenase utilizers were dependent on the overall rearing conditions, being the result of diet, environment, agrotechnical measures, and other factors combined. By sequencing of the 16S rRNA gene, archaea of the genus Methanomassiliicoccus (Candidatus Methanomassiliicoccus) were discovered in chickens for the first time. This study provides some indication that in chickens, acetogenesis may be the main metabolic pathway responsible for hydrogen sink.

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“…Other changes in the cecal microbiome included a significant decrease in Methanobrevibacter in the HN001 groups. In the gut, Methanobrevibacter primarily converts CO 2 and H 2 to form methane, although formate can also be used as substrate for methanogenesis ( 52 ). For methanogens, an important limiting factor is the concentration of H 2 , which in the gut is mainly produced by microbial fermentation of carbohydrates ( 53 ).…”

Section: Discussionmentioning

confidence: 99%

Lacticaseibacillus rhamnosus HN001 alters the microbiota composition in the cecum but not the feces in a piglet model

Young

Maclean²,

Dunstan³

et al. 2022

Front. Nutr.

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The probiotic Lacticaseibacillus rhamnosus strain HN001 has been shown to have several beneficial health effects for both pediatric and maternal groups, including reduced risk of eczema in infants and gestational diabetes and postnatal depression in mothers. While L. rhamnosus HN001 appears to modify immune and gut barrier biomarkers, its mode of action remains to be fully elucidated. To gain insights into the role of HN001 on the infant microbiome, the impacts of L. rhamnosus HN001 supplementation was studied in 10-day old male piglets that were fed either infant formula, or infant formula with L. rhamnosus HN001 at a low (1.3 × 105 CFU/ml) or high dose (7.9 × 106 CFU/ml) daily for 24 days. The cecal and fecal microbial communities were assessed by shotgun metagenome sequencing and host gene expression in the cecum and colon tissue was assessed by RNA-seq. Piglet fecal samples showed only modest differences between controls and those receiving dietary L. rhamnosus HN001. However, striking differences between the three groups were observed for cecal samples. While total lactobacilli were significantly increased only in the high dose L. rhamnosus HN001 group, both high and low dose groups showed an up to twofold reduction across the Firmicutes phylum and up to fourfold increase in Prevotella compared to controls. Methanobrevibacter was also decreased in HN001 fed piglets. Microbial genes involved in carbohydrate and vitamin metabolism were among those that differed in relative abundance between those with and without L. rhamnosus HN001. Changes in the cecal microbiome were accompanied by increased expression of tight junction pathway genes and decreased autophagy pathway genes in the cecal tissue of piglets fed the higher dose of L. rhamnosus HN001. Our findings showed supplementation with L. rhamnosus HN001 caused substantial changes in the cecal microbiome with likely consequences for key microbial metabolic pathways. Host gene expression changes in the cecum support previous research showing L. rhamnosus HN001 beneficially impacts intestinal barrier function. We show that fecal samples may not adequately reflect microbiome composition higher in the gastrointestinal tract, with the implication that effects of probiotic consumption may be missed by examining only the fecal microbiome.

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Hydrogen and formate production and utilisation in the rumen and the human colon

Cited by 28 publications

References 64 publications

Evaluating the efficacy of non-thermal microbial load reduction treatments of heat labile food components for in vitro fermentation experiments

Evaluating the efficacy of non-thermal microbial load reduction treatments of heat labile food components for in vitro fermentation experiments

Microorganisms Involved in Hydrogen Sink in the Gastrointestinal Tract of Chickens

Lacticaseibacillus rhamnosus HN001 alters the microbiota composition in the cecum but not the feces in a piglet model

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