Potential of yeast antagonists on invitro biodegradation of ochratoxin A

Six antagonistic yeast strains were screened initially for their ability to degrade Ochratoxin A (OTA) in liquid medium amended with OTA (7 5 mu g ml(-1)) and different concentrations of yeast cells at 30 degrees C Highest OTA degradation was observed when the yeast cell concentration used at 1 x 10(8) cells/ml ranging from 78 to 84% Out of six yeast strains three strains [Metschnikowia puicherrima (MACH1) pichia guilliemonodii (M8) and Rhodococcus erythropolis (AR14)] were selected for further studies In preliminary studies yeast strains were evaluated for their ability to degrade OTA at different temperature regimes (10 15 20 25 30 and 35 degrees C) and found that 30 degrees C was the optimum temperature for yeast growth and highest OTA degradation ranging from 104 to 83 5% These three strains were further evaluated to test their potential on OTA degradation using different concentrations of OTA (5 and 10 mu g ml(-1)) only at 30 degrees C Three strains showed more or less same results with that of 75 mu g ml(-1) concentration ranging from 75 to 81% The three yeast antagonists were further tested to confirm either degradation or cell wall adsorption of OTA at different time intervals Among the strains MACH1 effectively degraded the OTA (>80%) at 30 C after 15 days incubation compared to other strains tested and few amounts of OTA adsorption was observed in the yeast cell wall LC-MS studies revealed that no by-product like alpha-OT or Phenylalanine was found during the degradation process Therefore further studies are needed to understand the mechanism of action of these yeast strains during OTA degradation (C) 2010 Elsevier Ltd All rights reserved