Isolation and characterization of a novel gene for degradation of environmental pollutants from environmental genetic source

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It is difficult to isolate a novel gene or enzyme for degradation of environmental pollutants by using the conventional enrichment-culture method. We directly isolated and purified long chain DNA from soil environment, and constructed soil DNA library using cosmid vector. The resultant soil DNA library was introduced into the host strain that could not grow on naphthalene because of its lack of one of genes for naphthalene assimilation. The clones which grew on naphthalene were isolated. The gene that complemented the naphthalene assimilation ability of the strain did not show homology to knwon genes for naphthalene degradation. Furthermore, we constructed strains which could not grow on BHC or haloalkanes becuse of their lack of one of genes for assimilation of BHC or haloalkanes. By using these strains, it is theoretically possible to isolate novel genes for BHC dehydrochlorinase or haloalkane dehalogenase. Introduction of the soil DNA library into these stratns are in progress.