Ochratoxin A biodegradation by pediococcus parvulus

Abstract

Some lactic acid bacteria (LAB) have mycotoxin decontaminating properties due to the absorbing characteristics of their cells walls and because some can biotransform mycotoxins into less toxic compounds. One importante mycotoxin found in agricultural commodities is ochratoxin A (OTA). OTA is known mainly for its nephrotoxicity and carcinogenicity being classified in Group 2B by IARC. The present work reports on the ability of Pediococcus parvulus strains, which were isolated from Douro wines, to detoxify OTA. These strains were identified and characterised using a polyphasic approach that employed both phenotypic and genotypic methods. Strains were cultured in TA supplemented MRS media (1 g/mL) at different conditions. The influence of bacteria inoculum size, OTA concentration in MRS medium and incubation temperature was evaluated. OTA was biodegraded into OT by P. parvulus strains in all conditions but not by reference strains. OT was confirmed using LC-MS/MS. The conversion of OTA into OT indicates that OTA amide bond was hydrolysed by a putative peptidase. The rate of OTA biodegradation was found to be dependent on the bacteria inoculum size and on the incubation temperature. Under optimum conditions (109 CFU/mL and 30 ºC), 50% and 90% of OTA was degraded in 6 and 19 h, respectively. Dead cells of P. parvulus adsorbed only 1.3% of OTA, excluding this mechanism in the elimination of OTA by strains. OTA biodegradation by P. parvulus UTAD 473 was also evaluated and observed in grape must. Vinification experiments were also conducted. Because some P. parvulus strains have relevant probiotic properties, the strains that were identified could be particularly relevant to food and feed applications to counteract the toxic effects of OTA.