Rhodococcus pyridinivorans sp. nov., a pyridine-degrading bacterium.

The taxonomic position of a bacterial strain (PDB9T) that is capable of degrading pyridine was clarified by a polyphasic taxonomic approach using phenotypic, chemotaxonomic and genetic methods. The cells, which are rods and branched filaments during the early growth phase, fragment into short rods or cocci, thereby completing the growth cycle. Strain PDB9T was found to have a cell wall of chemotype IV, MK-8(H2) as the predominant menaquinone, mycolic acids with 36-46 carbon atoms and C16:0' C18:1 cis9, 10-methyl-C18:0 (TBSA) as the major fatty acids. The G+C content of the DNA was 66 mol%. The phylogenetic tree showed that strain PDB9T falls within an evolutionary radiation comprising Rhodococcus species and is most closely related to the type strain of Rhodococcus rhodochrous, sharing 99% 16S rDNA similarity. The differences in some phenotypic characteristics and the genetic distinctiveness distinguish strain PDB9T from the Rhodococcus species described previously. Therefore, strain PDB9T should be placed in the genus Rhodococcus as a new species, for which the new name Rhodococcus pyridinivorans sp. nov. is proposed. The type strain of the new species is strain PDB9T (= KCTC 0647BPT = KCCM 80005T).