Salipiger mucescens gen. nov., sp. nov., a moderately halophilic, exopolysaccharide-producing bacterium isolated from hypersaline soil, belonging to the α-Proteobacteria

Abstract

Salipiger mucescens gen. nov., sp. nov. is a moderately halophilic, exopolysaccharide-producing, Gram-negative rod isolated from a hypersaline habitat in Murcia in south-eastern Spain. The bacterium is chemoheterotrophic and strictly aerobic (i.e. unable to grow under anaerobic conditions either by fermentation or by nitrate or fumarate respiration). It does not synthesize bacteriochlorophyll a. Catalase and phosphatase are positive. It does not produce acids from carbohydrates. It cannot grow with carbohydrates or amino acids as sole sources of carbon and energy. It grows best at 9–10 % w/v NaCl and requires the presence of Na+ but not Mg2+ or K+, although they do stimulate its growth somewhat when present. Its major fatty-acid component is 18 : 1ω7c (78·0 %). The predominant respiratory lipoquinone found in strain A3T is ubiquinone with ten isoprene units. The G+C content is 64·5 mol%. Phylogenetic analyses strongly indicate that this strain forms a distinct line within a clade containing the genus Roseivivax in the subclass α-Proteobacteria. The similarity value with Roseivivax halodurans and Roseivivax halotolerans is 94 %. In the light of the polyphasic evidence gathered in this study it is proposed that the isolate be classified as representing a new genus and species, Salipiger mucescens gen. nov., sp. nov. The proposed type strain is strain A3T (=CECT 5855T=LMG 22090T=DSM 16094T).