Pangenome Analysis of Marine Nitrifiers Suggests Differences in Vitamin B12 Metabolism

Abstract

Nitrite-oxidizing bacteria are key players in the global nitrogen cycle, as they perform the oxidation of nitrite to nitrate in the dark ocean. However, relatively little is known about these microbes due to a lack of live cultured strains. This project sought to determine if the genomes of uncultured strains of nitrite oxidizers in the phylum Nitrospinae contained genes predicted to be involved in the synthesis pathway for vitamin B12, an important cofactor that assists with metabolism. Through the construction of a pangenome – a genomic analysis that allows for the comparison of gene presence across multiple related genomes – it was determined that genes predicted to be utilized in vitamin B12 synthesis were present in the Clade 2 subgroup of Nitrospinae and absent in other clades.