Enterobacter arachidis sp. nov., a plant-growth-promoting diazotrophic bacterium isolated from rhizosphere soil of groundnut

Abstract

A methylotrophic nitrogen-fixing bacterial strain, Ah-143T, isolated from the rhizosphere soil of field-grown groundnut was analysed by a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis combined with rpoB gene sequence analysis allocated strain Ah-143T to the family Enterobacteriaceae, with Enterobacter radicincitans and Enterobacter cowanii as the closest relatives. The strain is Gram-stain-negative, non-spore-forming, aerobic and motile, having straight rod-shaped cells with a DNA G+C content of approximately 53.2 mol%. The strain utilizes methanol as a carbon source and the mxaF gene was closely related to the mxaF gene of members of the genus Methylobacterium. The fatty acid profile consisted of C 16 : 0, C17 : 0 cyclo, C18 : 1ω7c, summed feature 2 (iso-C16 : 1 I and/or C14 : 0 3-OH) and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c) as the major components. DNA-DNA relatedness of strain Ah-143T with its close relatives was less than 20 %. On the basis of the phylogenetic analyses, DNA-DNA hybridization data, and unique physiological and biochemical characteristics, it is proposed that the strain represents a novel species of the genus Enterobacter and should be named Enterobacter arachidis sp. nov. The type strain is Ah-143T (=NCIMB 14469T =KCTC 22375 T).