Aquiflexum balticum gen. nov., sp. nov., a novel marine bacterium of the Cytophaga–Flavobacterium–Bacteroides group isolated from surface water of the central Baltic Sea

Abstract

A bacterial isolate from the Baltic Sea, BA160T, was characterized for its physiological and biochemical features, fatty acid profile, G+C content and phylogenetic position based on 16S rRNA gene sequences. The strain was isolated from the surface water of the central Baltic Sea during the decay of a plankton bloom. Phylogenetic analyses of the 16S rRNA gene sequence revealed a clear affiliation with the family ‘Flexibacteraceae’, and showed the closest phylogenetic relationship with the species Belliella baltica and Cyclobacterium marinum. The G+C content of the DNA was 38·4 mol%. The strain was red-coloured due to carotenoids, Gram-negative, rod-shaped, and catalase- and oxidase-positive. Growth was observed at salinities from 0 to 6 %, with an optimum around 1·5 %. Temperature for growth ranged from 4 to 40 °C, with an optimum around 30 °C. The fatty acids were dominated by branched-chain fatty acids (>87 %), with a high abundance of iso-C15 : 0 (23 %) and anteiso-C15 : 0 (19 %). According to its morphology, physiology, fatty acid composition, G+C content and 16S rRNA gene sequence, strain BA160T is considered to represent a new genus of the family ‘Flexibacteraceae’. Due to its aquatic origin, the name Aquiflexum balticum gen. nov, sp. nov. is suggested for the type species (type strain, BA160T=DSM 16537T=LMG 22565T=CIP 108445T) of the new genus.