To produce the health-associated metabolite propionate, gut microbes require vitamin B12 as a cofactor to convert succinate to propionate. B12 is sourced in the human gut from the unabsorbed dietary ...fraction and
microbial production. However, experimental data for B12 production by gut microbes is scarce, especially on their produced B12-analogues. Further, the promotion of propionate production by microbially-produced and dietary B12 is not yet fully understood. Here, we demonstrated B12 production in 6 out of 8
predicted B12-producing bacteria from the human gut. Next, we showed
that B12 produced by
,
and
promoted succinate to propionate conversion of two prevalent B12-auxotrophic gut bacteria,
and
. Finally, we examined the propiogenic effect of commercially available B12-analogues present in the human diet (cyano-B12, adenosyl-B12 and hydroxy-B12) at two doses. The low dose resulted in partial conversion of succinate to propionate for
when grown with adenosyl-B12 (14.6 ± 2.4 mM succinate and 18.7 ± 0.6 mM propionate) and hydroxy-B12 (13.0 ± 1.1 mM and 21.9 ± 1.2 mM), in comparison to cyano-B12 (0.7 ± 0.1 mM and 34.1 ± 0.1 mM). Higher doses of adenosyl-B12 and hydroxy-B12 resulted in significantly more conversion of succinate to propionate in both propionate-producing species, compared to the low dose. B12 analogues have different potential to impact the propionate metabolism of prevalent propionate producers in the gut. These results could contribute to strategies for managing gut disorders associated with decreased propionate production.
Vitamin B12 (cobalamin) is present in the human lower gastrointestinal tract either coming from the unabsorbed dietary fraction or from
production of the gut microbiota. However, it is unclear ...whether the gut microbial communities need exogenous B12 for growth and metabolism, or whether B12 in low and high levels could affect gut community composition and metabolite production. Here, we investigated
B12 production of human fecal microbiota and the effects of different levels of B12 (as cyanocobalamin) on composition and activity. Eight fecal communities from healthy human adults distributed over three enterotypes, dominated by
(
= 5),
(
= 1) or
(
= 2) were used to perform batch fermentations in Macfarlane medium supplemented with low B12 medium (Control, 5 ng/ml, within the tested fecal range), no B12 addition (NB12), and high B12 addition (ExtraB12, 2500 ng/ml). The microbiota community composition (qPCR, 16S rRNA metabarcoding), metabolic activity (HPLC-RI), and B12 levels (UHPLC-DAD) were measured after 24 h incubation at 37
C under strict anaerobic conditions. All fecal microbial communities produced B12 in the NB12 condition after 24 h, in the range from 152 ± 4 to 564 ± 25 ng/ml. None of the B12 treatments had an impact on total bacterial growth, community richness, diversity and total metabolite production, compared to the low B12 control. However, a significant increase of propionate was measured in ExtraB12 compared to NB12. Most taxonomic and metabolite changes compared to control incubations were donor-dependent, implying donor-microbiota-specific changes upon B12 treatments. Our
data suggest that healthy human adult gut microbial communities have the capacity to produce B12 at levels fulfilling their own requirements, independently of the initial B12 content tested in the donor's feces. Further, supplementation of exogenous dietary B12 may have limited impact on the healthy human gut microbial community composition and function.
In patients with inflammatory bowel diseases (IBD), dietary micronutrient intake is low and deficiencies are common. Besides the host, also the gut microbiota require micronutrients and low levels ...may disturb its functioning. Multi‐omics studies indeed detected shifts in micronutrient‐dependent microbial pathways in IBD. It is however not clear whether micronutrients may alleviate inflammation directly, by modulating the immune system, or also indirectly, by modulating the structure and function of the gut microbiota. The latter seems of particular interest, since the gut microbiota is one of the future therapeutic targets in IBD.
A review of the most recent available literature on relevant micronutrients in context of IBD and gut microbiota was conducted. An overview per relevant micronutrient on its role on gut bacterial growth, metabolism and host–microbe interactions during gut inflammation is provided.
Dietary micronutrients have potential to be part of future personalized microbiome‐targeted therapies in IBD, considering both the micronutrient status of the host and the gut microbiota. However, cohort studies together with integrated multi‐scale studies are needed to understand the mechanisms of micronutrient–microbiome–host interactions in IBD and to evaluate efficacy and safety of dietary micronutrient treatment strategies.
Low intake of dietary vitamins and minerals by inflammatory bowel disease (IBD) patients may impact the gut microbiota functioning during inflammation, which may further impact IBD pathogenesis. In this review, an overview of relevant micronutrients for IBD, what is known about their role on the gut microbes, their interaction with the gut in IBD, and their therapeutic potential is given.
Whole genome sequencing (WGS) is rapidly replacing other molecular techniques for identifying and subtyping bacterial isolates. The resolution or discrimination offered by WGS is significantly higher ...than that offered by other molecular techniques, and WGS readily allows infrequent differences that occur between 2 closely related strains to be found. In this investigation, WGS was used to identify the changes that occurred in the genomes of 13 strains of bacterial foodborne pathogens after 100 serial subcultures. Pure cultures of Shiga-toxin-producing Escherichia coli, Salmonella enterica, Listeria monocytogenes, and Vibrio parahaemolyticus were subcultured daily for 100 successive days. The 1st and 100th subcultures were whole-genome sequenced using short-read sequencing. Single nucleotide polymorphisms (SNPs) were identified between the 1st and final culture using 2 different approaches, and multilocus sequence typing of the whole genome was also performed to detect any changes at the allelic level. The number of observed genomic changes varied by strain, species, and the SNP caller used. This study provides insight into the genomic variation that can be detected using next-generation sequencing and analysis methods after repeated subculturing of 4 important bacterial pathogens.
