Microbial degradation mechanism of pyridine by Paracoccus sp. NJUST30 newly isolated from aerobic granules

Abstract

In this study, a pyridine-degrading strain namely NJUST30 was isolated from aerobic granules capable of degrading pyridine and was identified as Paracoccus sp. At incubation temperature of 30 °C, initial pH of 7.0 and initial pyridine concentration of 500 mg L−1, complete pyridine removal could be achieved within incubation period as short as 54 h. Pyridine biodegradation profile by NJUST30 could be well fitted by the first-order decay kinetic model, suggesting the recalcitrant nature of pyridine and the inhibitory effect of pyridine towards NJUST30. Major intermediates during pyridine biodegradation by NJUST30, including 2,4-dihydroxy-2H-pyridine-3-one, 2-carbonyl-succinic acid, 1,2-dihydro-pyridin-2-ol, piperidin-2-ol and 4-formylamino-butyric acid were identified through HPLC/MS. Based on these intermediates, a distinct pyridine biodegradation pathway via hydroxylation, pyridine ring cleavage, carbonylation and carboxylation was revealed for the first time.