COLONY INTERACTION AND SECONDARY METABOLITE PRODUCTION OF CHEESE-RELATED FUNGI IN DUAL CULTURE

Interactions between fungi used as starter cultures (Penicillium roque forti, Penicillium camemberti, Penicillium nalgiovense, and Geotrichum candidum) and fungal contaminants associated with cheese were investi gated on agar medium at two temperatures, 18 and 25 degrees C. Mutual inhibition on contact was the most common interaction observed. The on ly other interaction observed was inhibition of the contaminant, while the starter continued to grow, especially in dual cultures involving G. candidum as the starter culture. Dual cultures involving G. candidu m showed inhibition of production of the mycotoxins mycophenolic acid, roquefortin C, chaetoglobosin A, and cyclopiazonic acid produced by t he contaminants. An unknown metabolite was detected in considerably la rger quantity in dual cultures involving G. candidum compared to detec tion in single cultures. There was no correlation between detection of this metabolite and the observed interactions. The results show that G. candidum plays a major role in interactions between fungi on cheese .