Biodegradation of 3-methylpyridine by an isolated strain, Gordonia rubripertincta ZJJ

Methylpyridines are a class of highly toxic pyridine derivatives. In this study, a novel degrading bacterium was isolated for 3-methylpyridine (3-MP) degradation (Gordonia rubripertincta ZJJ, GenBank accession NO. OP430847.1; CCTCC M 2022975). The maximum specific degradation rate, half-saturation constant and inhibition constant were fitted to be 0.48 h^-1, 88.3 mg L^-1 and 924.0 mg L^-1, respectively. During 3-MP biodegradation, the lost total organic carbon was transformed into CO₂ (67.4 %) and biomass (32.6 %), and ammonia nitrogen was almost the sole inorganic species with a conversion rate of 36.3 %. Three metabolic pathways were possibly involved in 3-MP degradation: I) methyl oxidation followed by ring hydroxylation and hydrogenation; II) rupture of C=C and C-N bonds after ring reduction; III) initial ring hydroxylation. The study not only provides a novel strain for the high-efficient degradation of 3-MP, but also contributes to an in-depth understanding of 3-MP biotransformation.