Amorphus orientalis sp. nov., an exopolysaccharide-producing bacterium isolated from salt mine sediment

Abstract

A Gram-negative, moderately halophilic, non-motile, aerobic bacterium, designated strain YIM D10T, was isolated from a salt mine sediment sample from Yunnan, south-west China. The strain grew optimally in the presence of 3-8% NaCl and at 28 degrees C and pH 7.5. The polar lipid profile of strain YIM D10T comprised diphosphatidylglycerol, an unknown phospholipid and two unknown aminolipids. The major cellular fatty acids were C18:1omega7c (30.5%), C19:0 cyclo omega8c (29.3%) and C18:0 (13.2%). The respiratory quinone was ubiquinone 10 (Q-10). The genomic DNA G+C content was 65.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM D10T was closely related to Amorphus coralli RS.Sph.026T (96.8% gene sequence similarity). Results confirmed the placement of isolate YIM D10T within the genus Amorphus. However, DNA-DNA hybridization between strain YIM D10T and the type strain of the only recognized species of the genus Amorphus, A. coralli RS.Sph.026T, was 16.7%, showing clearly that the isolate constitutes a new genospecies. Strain YIM D10T could be clearly differentiated from A. coralli and other phylogenetic neighbours on the basis of some phenotypic, genotypic and chemotaxonomic features. Therefore, strain YIM D10T is considered to represent a novel species of the genus Amorphus, for which the name Amorphus orientalis sp. nov. is proposed; the type strain is YIM D10T (=DSM 21202T=CCTCC AA 208035T).