Selective Oxidation of 2-Methylnaphthalene to 2-Methyl-1-naphthol by Rhodococcus sp. M192

Abstract

About 6000 isolates of microorganisms assimilating methylketones (C₃-C₆) were tested for their selective oxidation of 2-methylnaphthalene to 2-methyl-1-naphthol. Strain M192 was the highest 2-methyl-1-naphthol producer and was classified as the genus Rhodococcus. The optimal conditions for the site-specific oxidation were studied using resting Rhodococcus sp. M192. The 2-methyl-1-naphthol productivity was specifically increased using methylethylketone as a carbon source, 1-propanol as a solvent to dissolve the substrate, and ethylxanthate or diethyldithiiocarbamate as an inhibitor of 2-naphthoic acid (side-product) production. In the presence of these compounds, 2-methylnaphthalene was specifically oxidized at the 1-position without the conversion to 2-naphthoic acid. The productivity of 2-methyl-1-naphthol was about 90 μM from 1 mM 2-methylnaphthalene.