Halomonas olivaria sp. nov., a moderately halophilic bacterium isolated from olive-processing effluents

Abstract

A moderately halophilic, Gram-stain-negative, non-sporulating bacterium designed as strain TYRC17T was isolated from olive-processing effluents. The organism was a straight rod, motile by means of peritrichous flagella and able to respire both oxygen and nitrate. Growth occurred with 0–25 % (w/v) NaCl (optimum, 7 %), at pH 5–11 (optimum, pH 7.0) and at 4–50 °C (optimally at 35 °C). It accumulated poly-β-hydroxyalkanoate granules and produced exopolysaccharides. The predominant fatty acids were C18 : 1ω7c, C16 : 1ω7c and C16 : 0. Ubiquinone 9 (Q-9) was the only respiratory quinone. The DNA G+C content of TYRC17T was 53.9 mol%. Phylogenetic analyses of 16S rRNA gene sequences revealed that the strain represents a member of the genus Halomonas and more precisely of the subgroup containing Halomonas sulfidaeris , H. titanicae , H. variabilis , H. zhanjiangensis , H. alkaliantarctica , H. boliviensis and H. neptunia . TYRC17T showed high 16S-rRNA sequence identities in particular with the three last species listed (99.4–99.5 %). A multilocus sequence analysis (MLSA) using the 23S rRNA, gyrB, rpoD and secA genes allowed clarifying the phylogenetic position of TYRC17T. This, combined with the level of DNA–DNA hybridization between TYRC17T and its closest relatives ranging from 21.6 % to 48.4 %, indicated that TYRC17T did not represent any of these species. On the basis of phenotypic and genotypic characteristics, and also genomic and phylogenetic evidence, it was concluded that strain TYRC17T represented a novel species of the genus Halomonas . The name Halomonas olivaria sp. nov. is proposed with TYRC17T ( = DSM 19074T = CCUG 53850BT) as the type strain.