Effect of volatile compounds produced by indigenous yeast isolated from grapes on growth, pks gene expression and OTA production by Aspergillus carbonarius.

PONSONE M.L; KUHN Y.G; CHIOTTA M. L; SCHMIDT HEYDT,M; GEISEN R; CHULZE , S.N

Rotterdam

Congreso; The World Mycotoxin Forum IUPAC; 2012

ISM -IUPAC

Ochratoxin A (OTA) is a mycotoxin produced by several species of the Aspergillus and Penicillium genera. Due to its toxicity to humans and animals the International Agency for Research on Cancer (IARC) has classified OTA as a group 2B carcinogen. This toxin can contaminate a wide variety of foodstuffs and maximum permitted levels have been established by the EU and other countries to reduce the risk of human exposure. Prevention through pre-harvest management is the best method for controlling OTA contamination. Biological control using antagonist microorganisms has been proposed for a long time as a good option to control plant pathogens and toxigenic fungi. One of the advantages of biocontrol is that it could be used together with fungicides reducing the environment and toxicological risks of the chemical compounds. Yeasts are good candidates to use as biological control agents due to their biology and non toxic properties. The mechanism most probably involved in filamentous fungi biocontrol by yeast is competition for essential factors, parasitism and production of fungal growth inhibiting compounds. Until now there is no information about the volatile compunds production by yeasts strains with antifungal properties against Aspergillus section Nigri. The aim of this work was to determine the effect of volatile compounds produced by indigenous yeasts, potential biocontrol agents isolated from grapes, on Aspergillus carbonarius growth, OTA pks expression and OTA production. Out of 100 yeast strains isolated, 40 were able to produce volatile compounds that affected Aspergillus carbonarius growth. The 5 more promissing strais were studied to evaluate the effect on OTA pks gene expression and OTA production. The results showed that there was a good correlation between the OTA biosynthesis gene expression and the phenotypic production of OTA under the presence or absence of the biocontrol yeasts strains. The external growth parameters also moderate mycotoxin biosynthesis via their influence on gene transcription.