Rhodococcus koreensis sp. nov., a 2,4-dinitrophenol-degrading bacterium.

A 2,4-dinitrophenol-degrading bacterial strain, DNP505T, which was isolated from an industrial wastewater, was taxonomically studied by a polyphasic approach using phenotypic, chemotaxonomic and genetic methods. Strain DNP505T has a cell wall of chemotype IV containing meso-diaminopimelic acid, arabinose and galactose. The predominant menaquinone is MK-8(H2). Mycolic acids contain 43-53 carbon atoms. Strain DNP505T has a cellular fatty acid profile containing straight-chain saturated, unsaturated and 10-methyl-branched fatty acids and has C16:0 as the major fatty acid. The DNA G+C content is 66 mol%. Strain DNP505T formed a coherent cluster with Rhodococcus species in a phylogenetic inference based on 16S rDNA sequences. Interestingly, strain DNP505T was found to have two types of 16S rDNA sequence, which showed 10 bp sequence differences (99.3% nucleotide similarity). Its differences in some phenotypic characteristics and its genetic distinctiveness indicate that strain DNP505T is separate from Rhodococcus species described previously. It is therefore proposed that strain DNP505T should be placed in the genus Rhodococcus as a new species, Rhodococcus koreensis. The type strain of the new species is strain DNP505T (= KCTC 0569BPT = JCM 10743T).