Defluvicoccus vanus gen. nov., sp. nov., a novel Gram-negative coccus/coccobacillus in the ‘Alphaproteobacteria’ from activated sludge

Abstract

A novel Gram-negative coccus/coccobacillus, strain Ben 114T, growing in tetrads, clusters or aggregates, was isolated from activated sludge by micromanipulation. 16S rRNA gene sequence analysis revealed that it belonged to the ‘Alphaproteobacteria’, with no close relatives among cultured bacterial isolates. On the basis of phylogenetic data, this organism is considered to belong to a new genus, Defluvicoccus, represented by the species Defluvicoccus vanus sp. nov., a name chosen because of the distinctive staining properties of this organism; only the cell wall stained strongly with a wide range of stains, giving the cell a hollow and empty appearance. No intracellular polyphosphate granules could be detected after staining, but poly-β-hydroxyalkanoate inclusions were detected using Nile blue A staining. Because of its taxonomic distance from its closest relatives among the ‘Alphaproteobacteria’, namely members of the genera Azospirillum, Phaeospirillum, Rhodospirillum, Rhodocista, Magnetospirillum and Rhodospira, D. vanus is considered to represent a new phylogenetic lineage within subgroup 1 of the ‘Alphaproteobacteria’, the D. vanus subgroup. The type strain is Ben 114T (=NCIMB 13612T=CIP 107350T).