Pichia anomalaas a biocontrol agent ofPenicillium roquefortiin high-moisture wheat, rye, barley, and oats stored under airtight conditions

Abstract

Pichia anomala inhibits growth of Penicillium roqueforti in high-moisture winter wheat, barley, and oats in cases where a malfunctioning airtight feed-storage system allows air to leak in. To imitate air leakage to such a storage system, grain was inoculated, packed in glass tubes with a restricted air supply, and incubated at 25°C. Yeast and mold colony-forming units (CFU) were counted on selective media after 14 days. Pichia anomala reached a density of about 5 x 107CFU/g on all tested cereals except in spring wheat (cv. Dragon), where a density of 109CFU/g was reached. In winter wheat (cv. Kosack), Penicillium roqueforti reached a density of 106CFU/g in grain that had not been inoculated with yeast and 105CFU/g in co-culture with 5 x 103CFU/g of Pichia anomala. At 5 x 104Pichia anomala, growth of Penicillum roqueforti was totally inhibited. Similar results were obtained with spring wheat (cv. Dragon), barley (cv. Golf), and oats (cv. Svea). However, spring wheat cv. Dragon was generally much less conducive to growth of Penicillium roqueforti. On rye (cv. Motto), Penicillium roqueforti did not grow in monoculture or when co-cultured with Pichia anomala. No differences in antagonistic activity of Pichia anomala or sensitivity of Penicillium roqueforti, respectively, were found between the three isolates tested of each species.Key words: biological control, postharvest, mold, cereal grain, storage.