Engineered nitrile hydratase-producing bacterium with amidase gene knocked-out, the construction and the use thereof

Abstract

An engineered nitrile hydratase-producing bacterium and its construction method as well as its applications, wherein the engineered nitrile hydratase-producing bacterium is a mutant strain of an original nitrile hydratase-producing bacterium strain obtained by knocking-out or inhibiting the amidase gene in the original strain. The construction method of the engineered bacterium is to block the expression of the amidase gene by inserting the large fragment of a recombinant suicide plasmid carrying an amidase gene fragment into a wild-type strain through the homologous recombination between the recombinant suicide plasmid and the amidase gene of the wild-type strain. Compared to the corresponding wild-type bacterium strain, both the cell growth and the nitrile hydratase expression of the engineered nitrile hydratase-producing bacterium according to the invention are increased. In the process of catalyzing the hydration of acrylonitrile to produce acrylamide, the yield of the product, acrylamide, is significantly increased, while the yield of the by-product acrylic acid is significantly decreased. The engineered nitrile hydratase-producing bacterium of the present invention has wide application prospect in the production of acrylamide by microbiological process.