Biosynthesis and cellular content of folate in bifidobacteria across host species with different diets

BACKGROUND: Bifidobacteria, one of the most common bacteria of the intestinal tract, help establish balance in the gut microbiota and confer health benefits to the host. One beneficial property is folate biosynthesis, which is dependent on species and strains. It is unclear whether the diversity in folate biosynthesis is due to the adaptation of the bifidobacteria to the host diet or whether it is related to the phylogeny of the animal host. To date, folate production has been studied in the bifidobacteria of omnivorous, and a few herbivorous, non-primate hosts and humans, but not in carnivores, non-human primates and insects. In our study we screened folate content and composition in bifidobacteria isolated from carnivores (dog and cheetah), Hominoidea omnivorous non-human primates (chimpanzee and orangutan) and nectarivorous insects (honey bee). RESULTS: Bifidobacterium pseudolongum subsp. globosum, a species typically found in non-primates, was isolated from dog and cheetah, and B. adolescentis and B. dentium, species typically found in humans, were respectively obtained from orangutan and chimpanzee. Evidence of folate biosynthesis was found in bifidobacteria isolated from non-human primates, but not from the bifidobacteria of carnivores and honey-bee. On comparing species from different hosts, such as poultry and herbivorous/omnivorous non-primates, it would appear that folate production is characteristic of primate (human and non-human) bifidobacteria but not of non-primate. Isolates from orangutan and chimpanzee had a high total folate content, the mean values being 7792 μg/100 g dry matter (DM) for chimpanzee and 8368 μg/100 g DM for orangutan. The tetrahydrofolate (H4folate) and 5-methyl-tetrahydrofolate (5-CH3-H4folate) distribution varied in the bifidobacteria of the different animal species, but remained similar in the strains of the same species: B. dentium CHZ9 contained the least 5-CH3-H4folate (3749 μ/100 g DM), while B. adolescentis ORG10 contained the most (8210 μg/100 g DM). CONCLUSION: Our data suggest a correlation between phylogenetic lineage and capacity of folate production by bifidobacteria, rather than with dietary type of the host.