Degradation of ochratoxin A and other mycotoxins by Rhizopus isolates

Several filamentous fungi representing the genera Rhizopus and Mucor were examined for their ability to degrade ochratoxin A (OTA), aflatoxin B1, zearalenone and patulin in a liquid medium. While none of the isolates exhibited aflatoxin degrading activity, ochratoxin A, zearalenone and patulin were decomposed by several isolates. Ochratoxin A was successfully degraded by Rhizopus stolonifer, R. microsporus, R. homothallicus and two R. oryzae isolates, and by four unidentified Rhizopus isolates. Kinetics of ochratoxin A detoxification of selected Rhizopus isolates was also examined. Rhizopus isolates were able to degrade more than 95% of ochratoxin A within 16 days. A R. stolonifer isolate could also effectively decompose ochratoxin A on moistened wheat. Further studies are in progress to identify the enzymes and genes responsible for ochratoxin detoxification and to transfer these genes to other Rhizopus isolates or microbes which could be used safely for decontamination of cereal products.