Effect of two Kluyveromyces thermotolerans strains, potential biocontrol agents, on polyketide synthase gene expression, ochratoxin A and B accumulation by Penicillium and Aspergillus ochratoxigenic species

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

World Mycotoxin Journal

Wageningen Academic Publishers

Lugar: Wageningen; Año: 2013 vol. 6 p. 291 - 297

1875-0710

In a previous study it was demosntrated that Kluyveromyces thermotolerans strains can reduce both growth and ochratoxin A (OTA) acumulation by Aspergillus section Nigri strains. There is no inormation about the mechanisms realted to this reduction. A viable hypothesis can be that the presence of biocontrol agents can affect OTA biosynthesis by influencing the transcriptional activity of the polyketide synthase (pks) gene one of the key enzymes in the OTA biosynthetic pathway. The aims of this work were to determine the effect of two selected strains of K. thermotolerans a spotential biocontrol agents and toe valuate if their presence can affect the ota pks gene expression of ochratoxigenic Aspergillus and Penicillium specie. Growth, OTA and ochratoxin B (OTB) biosynthesis by the fungal strains at the phenotypic and molecular levels were monitored. The results obtained showed that both K. thermotolernas strains evalauted had a strong influence on growth OTA and OTB biosynthesis and expression of mycotoxin biosynthesis genes. however no direct correlation between the influence of the biocntrol yeasts on pks gene expression OTA and OTB production could be found. These results could indicate an inhibitory mechanism by the yeasts which apparently involve a psot-tanscriptional mehcanism. The data obtained could imply that the production of mycotoxins canb e regarded as a kind of adpatation mechanism to environmental stress conditions by these mycotoxigenic species