Ochratoxin A accumulation in cultures of Penicillium verrucosum with the antagonistic yeast Pichia anomala and Saccharomyces cerevisiae

摘要

Growth and ochratoxin A accumulation by 2 isolates of Penicillium verrucosum, IBT5010 and IBT12803, were examined in co-cultures with Pichia anomala or S. cerevisiae. Each yeast was co-cultured with Penicillium verrucosum in malt extract agar supplemented with 1% yeast extract and incubated at 25deg C for 14 days. Ochratoxin A was stable at 25degree C, whether or not yeast was present. Pichia anomala and S. cerevisiae reduced mould growth to approx. the same extent in vitro. Both yeasts significantly reducedthe growth of Penicillium verrucosum isolates at 3X103 colony forming units (cfu)/plate. In all co-cultures in vitro accumulated ochratoxin A was reduced to below the detection limit (100 ng/plate) by yeast amounts as low as 3X102 cfu/plate. In wheat, the growth of P. verrucosum IBT5010, measured as cfu, was not reduced in the presence of Pichia anomala, while the growth of Penicillium verrucosum IBT12803 was clearly inhibited by this yeast. A similar pattern was observed for ochratoxin A accumulationin wheat when the 2 mould strains were co-cultured with Pichia anomala. Mycotoxin production was more sensitive to the presence of yeasts than was mould growth. Co-cultivation with yeasts gave no detectable stimulation of ochratoxin A accumulation in agar or wheat.