Rhodovulum imhoffii sp. nov.

Abstract

A yellowish-brown bacterium was isolated from photoheterotrophic enrichment cultures obtained from water samples of an aquaculture pond at Bhimunipatnam, India. Enrichment and isolation in a medium containing 2 % NaCl (w/v) yielded strain JA125T, the cells of which were rod-shaped and non-motile. On the basis of the 16S rRNA gene sequence, strain JA125T belongs to the class Alphaproteobacteria and is closely related to the type strains of Rhodovulum iodosum (96 %), Rhodovulum adriaticum (95 %), Rhodovulum robiginosum (95 %), Rhodovulum sulfidophilum (94 %) and Rhodovulum marinum (94 %). The cells of strain JA125T contained vesicular internal membranes and bacteriochlorophyll a and carotenoids of the spheroidene series. Strain JA125T grew optimally at 28 °C and at pH 7.0–8.0. The best growth occurred photoheterotrophically with a number of organic compounds serving as carbon sources and electron donors. The strain grew photoautotrophically, but chemoautotrophic growth did not occur. Strain JA125T was able to utilize sulfide, sulfate, thiosulfate and thioglycolate as sulfur sources. Biotin was required as a growth factor. The DNA G+C content was 58 mol%. On the basis of 16S rRNA gene sequence analysis and the morphological and physiological data, strain JA125T is significantly different from other species of the genus Rhodovulum and represents a novel species, for which the name Rhodovulum imhoffii sp. nov. is proposed. The type strain is JA125T (=JCM 13589T=DSM 18064T).