Effects of carnitine acetyltransferase gene knockout on long chain dicarboxylic acid production and metabolism of Candida tropicalis

Candida tropicalis can assimilate n-alkane as a sole carbon source and produce dicarboxylic acids (DCAs). The synthesis of DCAs is thought to be reduced by beta-oxidation. Carnitine acetyltransferase (CAT) is the major enzyme to transfer DCAs into beta-oxidative pathway, then DCAs would be catalyzed to generate ATP to supply cells with energy. A homologous recombination plasmid was constructed, in which CAT gene was disrupted by inserting hygromycin B resistance gene. This plasmid was used to transform Candida tropicalis wild type strain F10-1, and one single CAT gene knockout strain was obtained. Comparing with the wild type, the recombinant increased DCA13 yield and molar conversion of alkane by 13.0% and 11.8%, respectively, and decreased unnecessary consumption of DCAs in beta-oxidation.