(formerly ) B-276, isolated with propene as sole carbon and energy source, is able to oxidize trichloroethene (TCE). Glucose- or propene-grown B-276 cells exhibited no difference in TCE degradation efficiency. TCE degradation was found to be growth-phase-dependent and maximum rates were monitored with stationary-phase cells. and values for TCE degradation of B-276 grown in nutrient broth medium in the presence of glucose were 187 μM and 2·4 nmol min (mg protein), respectively. recombinants harbouring and expressing the alkene monooxygenase genes of B-276 exhibited the ability to degrade TCE. This result provides clear evidence that the alkene monooxygenase of B-276 catalyses TCE oxidation. B-276 was shown to contain four linear plasmids, pNC10 (70 kb), pNC20 (85 kb), pNC30 (185 kb) and pNC40 (235 kb). The observation that pNC30-deficient strains had lost the ability to grow on propene suggested that the genes of the propene degradation pathway are encoded by the linear plasmid pNC30. Southern blot analysis with cloned alkene monooxygenase genes from B-276 revealed a positive hybridization signal with the linear plasmid pNC30. This result clearly shows that the alkene monooxygenase is encoded by the linear plasmid pNC30. Eleven short-chain-alkene-oxidizing strains were screened for the presence of linear plasmids. Among these, four propene-oxidizing strains and one ethene-oxidizing strain were found to contain linear megaplasmids. Southern blot analysis with the alkene monooxygenase revealed positive signals with linear plasmids of two propene-oxidizing strains. These results indicate that homologous alkene monooxygenases are encoded by linear plasmids in strains.


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