Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/5/2006
Publication Date: 12/1/2006
Citation: Liang, Y., Gardner, D.R., Miller, C.D., Chen, D., Anderson, A.J., Weimer, B.C., Sims, R. 2006. Study of Biochemical Pathways and Enzymes Involved in Pyrene Degradation by Mycobacterium sp. Strain KMS. Applied and Environmental Microbiology Vol. 72, No. 12, pp. 7821-7828. Interpretive Summary: Pyrene is a four-ring polycyclic aromatic hydrocarbon (PAH) and is currently under investigation as to its biodegradation by micro bacteria in contaminated soils. Mycobacterium sp. KMS is a new strain of bacteria isolated from a Superfund site in Libby Montana which has been found to degrade pyrene and was used here in this study to isolate and identify pyrene metabolites and the enzymes involved in pyrene degradation. Key pyrene metabolites identified were pyrene-4,5-dione, cis-4,5-pyrene-dihydrodiol, phenanthrene-4,5-dicarboxylic acid and 4-phenanthroic acid. From the metabolite identifications a pyrene degradation pathway was proposed and confirmed by the identification of all the enzymes required during the initial steps of the biodegradation. Information from this study will provide the basic scientific information and knowledge for understanding, control and improvement of the bioremediation process at PAH-contaminated sites.
Technical Abstract: Pyrene degradation is known in bacteria. In this study, Mycobacterium sp. Strain KMS was used to study the metabolites produced during, and enzymes involved in, pyrene degradation. Several key metabolites, including pyrene-4,5-dione, cis-4,5-pyrene-dihydrodiol, phenanthrene-4,5-dicarboxylic acid, and 4-phenanthroic acid, were identified during pyrene degradation. Pyrene-4,5-dione, which accumulates as an end product in some gram-negative bacterial cultures, was further utilized and degraded by Mycobacterium sp. Strain KMS. Enzymes involved in pyrene degradation by Mycobacterium sp. Strain KMS were studied, using 2-D gel electrophoresis. The first protein in the catabolic pathway, aromatic-ring-hydroxylating dioxygenase, which oxidizes pyrene to cis-4,5-pyrene-dihydrodiol, was induced with the addition of pyrene and pyrene-4,5-dione to the cultures. The subcomponents of dioxygenase, including the alpha and beta subunits, 4Fe-4S ferredoxin, and the Rieske (2Fe-2S) region, were all induced. Other proteins responsible for further pyrene degradation, such as dihydrodiol dehydrogenase, oxidoreductase, and epoxide hydrolase, were also found to be significantly induced by the presence of pyrene and pyrene-4,5-dione. Several nonpathway-related proteins, including sterol-binding protein and cytochrome P450 were induced. A pyrene degradation pathway for Mycobacterium sp. Strain KMS was proposed and confirmed by proteomic study by identifying almost all the enzymes required during the initial steps of pyrene degradation.