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

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 degrees 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.