Real-time PCR detection of Fe-type nitrile hydratase genes from environmental isolates suggests horizontal gene transfer between multiple genera

Nitriles are widespread in the environment as a result of biological and industrial activity. Nitrile hydratases catalyse the hydration of nitriles to the corresponding amide and are often associated with amidases, which catalyze the conversion of amides to the corresponding acids. Nitrile hydratases have potential as biocatalysts in bioremediation and biotransformation applications, and several successful examples demonstrate the advantages. In this work a real-time PCR assay was designed for the detection of Fe-type nitrile hydratase genes from environmental isolates purified from nitrile-enriched soils and seaweeds. Specific PCR primers were also designed for amplification and sequencing of the genes. Identical or highly homologous nitrile hydratase genes were detected from isolates of numerous genera from geographically diverse sites, as were numerous novel genes. The genes were also detected from isolates of genera not previously reported to harbour nitrile hydratases. The results provide further evidence that many bacteria have acquired the genes via horizontal gene transfer. The real-time PCR assay should prove useful in searching for nitrile hydratases that could have novel substrate specificities and therefore potential in industrial applications.