The Bacillus strain BH072 isolated from a honey sample showed strong antifungal activity against phytopathogen. Gene cloning test demonstrated that the strain had a tas A gene encoding an antifungal Tas A protein. Although the wild strain simultaneously produced various antifungal substances, only the physicochemical property and antifungal activity of Tas A protein were unclear due to the difficulty in extraction. In this study, tas A gene encoding the protein from Bacillus sp. BH072 was amplified by using the polymerase chain reaction(PCR) method and cloned into p ET 28a(+) vector, and then expressed in host cells Escherichia coli BL21(DE3). The expressed proteins were collected by centrifugation and ultrasonic treatment, and then purified by using nickel-nitrilotriacetic acid(Ni-NTA)metal affinity column and dialysis methods. The result of sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) test showed that an expected protein band appeared with a size of 31 k Da. The expressed products possessed antifungal activity against the phytopathogenic indicator strain Botrytis cinerea. A genetically engineered strain tas A of E. coli was established in this study which can efficiently express Tas A protein.
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