Shinella daejeonensis sp. nov., a nitrate-reducing bacterium isolated from sludge of a leachate treatment plant

Abstract

A Gram-negative-staining, motile, rod-shaped, aerobic bacterial strain, designated MJ02T, was isolated from sludge of a leachate treatment plant in Daejeon (South Korea) and was characterized to determine its taxonomic position by using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain MJ02T belonged to the family Rhizobiaceae, class Alphaproteobacteria, and was most closely related to Shinella yambaruensis MS4T (97.6 % sequence similarity) and Shinella fusca DC-196T (97.5 %). The G+C content of the genomic DNA of strain MJ02T was 64.3 mol%. The detection of a quinone system with ubiquinone Q-10 as the predominant respiratory lipoquinone and a fatty acid profile with C18 : 1ω7c (45.8 %) and C16 : 0 (21.8 %) as the major components supported the affiliation of strain MJ02T to the genus Shinella. However, strain MJ02T exhibited relatively low levels of DNA–DNA relatedness with respect to S. fusca DSM 21319T (17±7 %) and S. yambaruensis KACC 14483T (12±6 %), showing clearly that the isolate constituted a new genospecies. Strain MJ02T could be clearly differentiated from its phylogenetic neighbours on the basis of several phenotypic, genotypic and chemotaxonomic features. Therefore, strain MJ02T is considered to represent a novel species of the genus Shinella, for which the name Shinella daejeonensis sp. nov. is proposed. The type strain is MJ02T ( = KCTC 22450T = JCM 16236T).