Rhodomicrobium lacus sp. Nov., an alkalitolerent bacterium isolated from umiam lake, Shillong, India

Abstract

A Gram-stain-negative, motile, alkali-tolerant, swollen-rod shaped, reddish brown coloured, phototrophic bacterium designated as strain JA980T, was isolated from freshwater sampled at Umiam lake, Shillong, India. Strain JA980T grew well up to pH 9.0. Respiratory quinones were ubiquinone 10 and rhodoquinone 10. The major fatty acid was C18:1 ω7c/C18:1 ω6c with minor amounts of C18:0, C16:0, C18:0 3-OH and C16:0 3-OH. Strain JA980T contained bacteriochlorophyll-a and carotenoids of the spirilloxanthin series. The polar lipids of strain JA980T comprised phosphatidylethanolamine, phosphatidylcholine, diphosphatidylglycerol, an unidentified phospholipid, unidentified amino lipids (AL1,3,4,5) and an unidentified lipid (L1). Strain JA980T had the highest (99.57%) 16S rRNA gene sequence similarity to the type strains of Rhodomicrobium vannielii ATCC17100T and Rhodomicrobium udaipurense JA643T. The genome of strain JA980T was 3.88 Mbp with a DNA G+C content of 62.4mol%. Based on the results of phylogenetic analyses, low in silico DNA–DNA hybridization values (33%), low (87%) average nucleotide identity results, chemotaxonomic characteristics and differential physiological properties, strain JA980T could not be classified into either of the two recognized species of the genus Rhodomicrobium, suggesting that it represents a novel species, for which the name Rhodomicrobium lacus sp. nov. is proposed. The type strain is JA980T (=KCTC 15697T= MCC 3714T= NBRC 113803T).