Phylogenetic Relationships of the Hard-to-Culture Bacterial Phylum 'Verrucomicrobia'

Abstract

The phylum 'Verrucomicrobia' represents a primary lineage within the bacterial phylum and contains a number of environmental clones as well as a small number of cultured species. Despite wide ecological distribution of representatives of the phylum 'Verrucomicrobia' in nature, owing to relatively few pure cultivated and characterized species, the classification of this phylum is still ambiguous and informal. For this reason, for formal classification of the phylum 'Verrucomicrobia', it is recommended that many verrucomicrobia that thrives in a wide range of terrestrial, aquatic and marine habitats should be isolated and taxonomically investigated. In this study, we attempted to elucidate the phylogenetic relationships of the thirty novel isolates using polyphasic taxonomic approaches including 16S rRNA and gyrB gene sequence analysis, together with molecular, physiological, biochemical and chemotaxonomic analyses to characterize the novel strains. Based on these data, it is proposed that these isolates represent seven novel genera and twenty-two new species within the phylum 'Verrucomicrobia'. Furthermore, with these novel strains, the formal classification of the phylum 'Verrucomicrobia，is established.