Rhodovulum mangrovi sp. nov., a phototrophic alphaproteobacterium isolated from a mangrove forest sediment sample

Abstract

A novel Gram-staining-negative, purple non-sulfur bacterium, strain AK41T, was isolated from a sediment sample collected from Coringa mangrove forest, Andhra Pradesh, India. A red–brownish-coloured culture was obtained on modified Pfennig medium after enrichment with 2% NaCl and 0.3% pyruvate under 2000 lx illumination. Individual cells were ovoid–rod-shaped and non-motile. Bacteriochlorophyll a and carotenoids of the spheroidene series were present as photosynthetic pigments. Strain AK41T was halophilic and grew photoheterotrophically with a number of organic compounds as carbon sources and electron donors. It was unable to grow photoautotrophically. It did not utilize sulfide or thiosulfate as electron donors. The fatty acids were found to be dominated by C16:0 and C18:1 omeaga 7c. Strain AK41T contained phosphatidylglycerol, phosphatidylethanolamine, an unknown aminolipid and four unknown lipids as polar lipids. Q-10 was the predominant respiratory quinone. The DNA G+C content of strain AK41T was 68.9 mol%. 16S rRNA gene sequence analysis indicated that strain AK41T was a member of the genus Rhodovulum and was closely related to Rhodovulum sulfidophilum, with 96.0% similarity to the type strain; the 16S rRNA gene sequence similarity to the type strains of other species of the genus Rhodovulum was 93.9–95.8%. Phylogenetic analyses indicated that strain AK41T clustered with the type strains of Rhodovulum marinum, Rdv. kholense, Rdv. sulfidophilum and Rdv. visakhapatnamense with sequence similarity of 95.9–96.2%. Based on data from the current study, strain AK41T is proposed to represent a novel species of the genus Rhodovulum, for which the name Rhodovulum mangrovi sp. nov. is proposed. The type strain of Rhodovulum mangrovi is AK41T (=MTCC 11825T =JCM 19220T)