Characterization of Rhodococcus wratislaviensis, a New Gram-Positive Facultative Methylotroph, and Properties of Its C1 Metabolism

A facultative methylotroph, strain 2AzMo (VKM Ac-2782), was isolated from the coastal zone of the Sea of Azov. The cells of the isolate are aerobic gram-positive nonmotile rods. Optimal growth occurs at 1% NaCl, 28 degrees C, and pH 7.5 with 1% CH3OH or 0.3% methylamine as the carbon and energy sources. A broad spectrum of polycarbon substrates is also utilized. Sequencing of the 16S rRNA gene of the strain revealed its similarity to Rhodococcus species: 99.9% to R. wratislaviensis IEGM 1112(T) (=NCIMB 13082(T)), 99.4% to R. imtechensis IEGM 940(T) (=RKJ300(T)), and 99.2% to R. koreensis IEGM 962(T) (=DNP505(T)). The level of DNA-DNA homology of strain 2AzMo with R. wratislaviensis IEGM 1112(T) (=NCIMB 13082(T)) was 76%, supporting its identification as a strain of this species. However, unlike strain 2AzMo, the type strain R.wratislaviensis IEGM 1112(T), as well as other members of this genus (R. imtechensis IEGM 940(T), R. koreensis IEGM 962(T), and R. opacus IEGM 716(T)), do not grow on methanol and methylamine. Methanol oxidation by R.wratislaviensis 2AzMo is catalyzed by alcohol dehydrogenase, which uses 4-nitroso-N,N-dimethylaniline as an artificial electron acceptor. Methylamine is oxidized by methylamine dehydrogenase and theenzymes of the N-methylglutamate pathway. Formaldehyde is then assimilated via the fructose bisphosphate aldolase variant of the ribulose monophosphate pathway of C-1 metabolism. Ammonium is assimilated by -ketoglutarate reductive amination and via the glutamate cycle.