Purification and characterization of the enzymes from Brevundimonas naejangsanensis that degrade ochratoxin A and B

Ochratoxin A (OTA) and Ochratoxin B (OTB) co-contaminate many types of agricultural products. Screening enzymes that degrade both OTA and OTB has significance in food safety. In this study, four novel OTA and OTB degrading enzymes, namely BnOTase1, BnOTase2, BnOTase3, and BnOTase4, were purified from the metabolites of the Brevundimonas naejangsanensis ML17 strain. These four enzymes hydrolyzed OTA into OTα and hydrolyzed OTB into OTβ. BnOTase1, BnOTase2, BnOTase3, and BnOTase4 have the apparent Km values for hydrolyzing OTA of 19.38, 0.92, 12.11, 1.09 μmol/L and for hydrolyzing OTB of 0.76, 2.43, 0.60, 0.64 μmol/L respectively. OTα and OTβ showed no significant cytotoxicity to HEK293 cells, suggesting that these enzymes mitigate the toxicity of OTA and OTB. The discovery of the novel OTA and OTB degrading enzymes enriches the research on ochratoxin control and provides objects for protein rational design.