Luteimonas sp. CW574 in Two Mycotoxins Degradation and Characterization of a Novel Detoxifying Amidohydrolase AMD3

Aflatoxin B1 (AFB1) and ochratoxin A (OTA) are the two most widely contaminated and highly toxic mycotoxins found in agro-products. A difunctional strain, Luteimonas sp. CW574, which can degrade AFB1 and OTA, was isolated and characterized. Herein, AFB1 was efficiently degraded by thermotolerant nonprotein chemical at 70-90°C, with degradation ratio of 100% at 90°C, and the active component was distributed in cell-free supernatant of bacterial culture. Meanwhile, OTA was hydrolyzed by a novel amidohydrolase AMD3, which was the intracellular detoxifying enzyme of the strain CW574. Amidohydrolase AMD3 showed superefficient activity to OTA, and 45 µg/L of OTA was degraded entirely by 1.0 µg/mL rAMD3 within 9 min. Amino acid residues of H95, H97, F100, K221, H262, H282, and D355 in AMD3 were predicted and verified as the critical active sites by protein structure-based assays. Based on molecular docking and mutant verification, the catalytic site of AMD3 may involve H95, H97, K221, or H282; however, these residues differ from the catalytic site of other amidohydrolases in superfamily 1 (e.g., D344 in amidohydrolase ADH3), indicating that AMD3 represents a novel hydrolase within this superfamily 1. Collectively, strain CW574 exhibits promising potential for detoxification of multiple mycotoxins in foodstuffs. PRACTICAL APPLICATIONS: AFB1 and OTA pose a serious threat to food safety and strain Luteimonas sp. CW574 can detoxify the mycotoxins.