Detoxification of Ochratoxin a by Weizmannia coagulans CGMCC 9951: Characterization, Mechanism, and Application in Cornus officinalis Pulp

This study investigates the degradation characteristics, pathways, and mechanisms of ochratoxin A (OTA) by Weizmannia coagulans CGMCC 9951 (W. coagulans CGMCC 9951), as well as its detoxification effect on Cornus officinalis pulp through fermentation. The strain efficiently degraded 300 ng/mL of OTA within 72 h (98% degradation) under optimal conditions of 37 °C, pH 5.0, and 180 rpm. Active degradation substances were primarily localized in the cell-free supernatant (CF). The degradation activity was significantly inhibited by heat treatment, proteinase K, EDTA, Cu2+, and organic reagents, suggesting an enzymatic mechanism. UHPLC-MS and MS/MS analysis indicated that OTA appears to be degraded to a product consistent with ochratoxin α (OTα). Based on homology to known OTA-degrading carboxypeptidases, the gene encoding WGU28473.1 was selected, expressed in E. coli, and confirmed to possess OTA-degrading activity. Molecular docking suggested potential interactions between the enzyme and OTA. Under optimal conditions, co-fermentation with Cornus officinalis pulp contaminated with 300 ng/mL OTA for 96 h resulted in a 74% degradation of OTA. The fermentation process increased the pulp’s sugar content and ABTS+ free radical scavenging capacity, reduced acidity, and improved the safety of the pulp. These findings demonstrate that W. coagulans CGMCC 9951 efficiently degrades OTA and improves pulp quality, highlighting its potential as a starter culture for detoxifying OTA-contaminated food.