Martelella mediterranea gen. nov., sp. nov., a novel α-proteobacterium isolated from a subterranean saline lake

Abstract

A bacterial strain was isolated from the water of Lake Martel in Mallorca (Spain). The isolate, designated MACL11T, was halotolerant and strictly aerobic. The cells were non-motile, non-spore-forming, Gram-negative short rods. Comparative 16S rRNA gene sequence analysis revealed that MACL11T represents a separate line of descent within the order ‘Rhizobiales’ of the class ‘Alphaproteobacteria’. Strain MACL11T was most closely related to the genera Rhizobium (93·3 % sequence similarity to Rhizobium rhizogenes), Aurantimonas (90·3 % sequence similarity to Aurantimonas coralicida) and Fulvimarina (90·3 % sequence similarity to Fulvimarina pelagi). Chemotaxonomically, strain MACL11T was characterized by the presence of Q-10 as the major respiratory lipoquinone. The major fatty acids detected were C19 : 0 cycloω8c, C18 : 1 ω7c, C16 : 0 and 11-methyl C18 : 1 ω7c. The G+C content of the DNA was 57·4 mol%. Oxidase and catalase activities were present. Growth with many different carbohydrates as the sole carbon source was observed. The data from this polyphasic study suggest that this bacterium belongs to a novel genus of the order ‘Rhizobiales’ and is not associated with any of the known families of this order. It is proposed that isolate MACL11T should be classified in a novel genus and species, Martelella mediterranea gen. nov., sp. nov., with MACL11T (=LMG 22193T=CECT 5861T) as the type strain.