Effect of the biocontrol yeast Pichia anomala on interactions between Penicillium roqueforti, Penicillium carneum, and Penicillium paneum in moist grain under restricted air supply

Abstract

Abstract Penicillium roqueforti was recently reclassified into the three species P. roqueforti, Penicillium carneum, and Penicillium paneum based on differences in ribosomal DNA sequences and secondary metabolites, e.g. mycotoxins. This is the first report on interaction between these closely related mould species under stress conditions. The yeast Pichia anomala (J121) inhibits growth of P. roqueforti in grain stored in malfunctioning airtight storage systems. The ability of P. anomala to inhibit all three species of the P. roqueforti group was examined in separate experiments as well as the competition between the three mould species when co-cultured with or without the yeast in non-sterile wheat grain (aw 0.95) under restricted air supply. Mould growth was analysed by dilution plating after 14 days and the individual colonies identified by random amplified polymorphic DNA (RAPD) fingerprinting. When co-culturing the P. roqueforti group in wheat without P. anomala all three species were able to grow to the same extent. Also, when co-culturing all species of the P. roqueforti group together with P. anomala, the growth response of the three species was very similar. At yeast levels of 104 CFU g−1 grain a pronounced inhibition was observed and at 105 CFU g−1 grain a fungicidal effect was detected, indicating a potentiated effect of P. anomala when co-culturing the three mould species.