Saccharospirillum impatiens gen. nov., sp. nov., a novel gamma-Proteobacterium isolated from hypersaline Ekho Lake (East Antarctica)

Abstract

Five Gram-negative, motile, aerobic to microaerophilic spirilla were isolated from various depths of the hypersaline, heliothermal and meromictic Ekho Lake (East Antarctica). The strains are oxidase- and catalase-positive, metabolize a variety of sugars and carboxylic acids and have an absolute requirement for sodium ions. The predominant fatty acids of the organisms are C(16 : 1)omega7c, C(16 : 0) and C(18 : 1)omega7c, with C(10 : 1))3-OH, C(10 : 0) 3-OH, C(12 : 0) 3-OH, C(14 : 1)3-OH, C(14 : 0) 3-OH and C(19 : 1) present in smaller amounts. The main polar lipids are diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylmonomethylamine. The DNA base composition of the strains is 54-55 mol% G + C. 16S rRNA gene sequence comparisons show that the isolates are related to the genera Oceanospirillum, Pseudospirillum, Marinospirillum, Halomonas and Chromohalobacter in the gamma-Proteobacteria. Morphological, physiological and genotypic differences from these previously described genera support the description of a novel genus and species, Saccharospirillum impatiens gen. nov., sp. nov. The type strain is EL-105(T) (=DSM 12546(T) = CECT 5721(T)).