2-Pyridone - Environmental Behavior

Environmental Behavior

2-Pyridone is rapidly degraded by microorganisms in the soil environment, with a half life less than one week. Organisms capable of growth on 2-pyridone as a sole source of carbon, nitrogen, and energy have been isolated by a number of researchers. The most extensively studied 2-pyridone degrader is the gram positive bacterium, Arthrobacter crystallopoietes, a member of the phylum, Actinobacteria, which includes numerous related organisms that have been shown to degrade pyridine or one or more alkyl-, carboxyl-, or hydroxyl-substituted pyridines. 2-Pyridone degradation is commonly initiated by mono-oxygenase attack, resulting in a diol, such as 2,5-dihydroxypyridine, which is metabolized via the maleamate pathway. Fission of the ring proceeds via action of 2,5-dihydroxypyridine monooxygenase, which is also involved in metabolism of nicotinic acid via the maleamate pathway. In the case of Arthrobacter crystallopoietes, at least part of the degradative pathway is plasmid-borne. Pyridine diols undergo chemical transformation in solution to form intensely colored pigments. Similar pigments have been observed in quinoline degradation, also owing to transformation of metabolites, however the yellow pigments often reported in degradation of many pyridine solvents, such as unsubstituted pyridine or picoline, generally result from overproduction of riboflavin in the presence of these solvents. Generally speaking, degradation of pyridones, dihydroxypyridines, and pyridinecarboxylic acids is commonly mediated by oxygenases, whereas degradation of pyridine solvents often is not, and may in some cases involve an initial reductive step.