Correlation of gene content in selected bifidobacteria with folate supplier or scavenger status during growth in laboratory media

Five different bifidobacterial cultures were screened to investigate if their de novo folate production ability could be predicated based on their folate biosynthetic gene content. As previously developed folate free media could not adequately support the growth of these five strains, even with added folate, an alternative medium (YNB+) was developed. Consistent with its genome prediction, Bifidobacterium animalis subsp. lactis strain Bb-12 required folate for its growth even in the presence of p-aminobenzoic acid (PABA). Although B. longum DJO10A and B. breve ATCC 15701 lack an alkaline phosphatase gene for the formation of one pathway intermediate (DHPPP), both were found to be able to grow independent from folate and PABA suggesting that lack of these genes in genome annotations cannot be used to predict folate dependency in bifidobacteria. Similarly, having all required genes cannot always predict folate production, as B. longum subsp. infantis RECb4 contained a full set of pathway genes, but required folate or PABA for growth. While many bifidobacteria can produce folate, this also cannot be used to predicate their ability to supply folate as some can act as scavengers when folate is readily available in the environment, such as B. breve ATCC 15701 in this study. As bifidobacterial cultures are sometimes considered for use in foods based on their folate production abilities, it is important to consider whether they function as folate scavengers or suppliers when growing in folate containing media.

Automated summary

Five different bifidobacterial cultures were tested for their de novo folate production ability based on their folate biosynthetic gene content. A new medium (YNB+) was developed as the previous folate-free media could not support their growth. The presence of certain genes or the absence of others in the genome annotations cannot accurately predict their folate dependency.