Effect of Kluyveromyces thermotolerans on OTA pks gene expression and toxin production by ochratoxigenic Penicillium and Aspergillus species

PONSONE, M.L.; SCHMIDT-HEYDT, M.; GEISEN, R.; CHULZE, S.N.

Rotterdam

Congreso; 7th conference of the World Mycotoxin Forum adn XIIIth IUPAC International Symposium on Mycotoxins and Phycotoxins.; 2012

IUPAC

Ochratoxin A (OTA) is a mycotoxin produced by species that belong mainly to the Aspergillus and Penicillium genera and occurs on different commodities such as cereals, coffee, cocoa beans, dried fruits, grapes and wine. Biological control offers a tool to reduce the impact of ochratoxigenic species. In previous studies we have demonstrated that Kluyveromyces thermotolerans strains can control both, growth and ochratoxin A production of Aspergillus section Nigri strains. There is no information about the mechanisms related to this control; a viable hypothesis can be that the presence of the biocontrol agents can affect OTA biosynthesis by affecting the transcription patterns of the pks enzyme, one of the key enzymes in the OTA biosynthetic pathway. The aim of this work was: -to determine the effect of two strains of Kluyveromyces thermotolerans (RCKT4 and RCKT5) on OTA pks expression by ochratoxigenic species including Penicillium nordicum (BFE487), Penicillium verrucosum (BFE808), Aspergillus carbonarius (RC13I) and Aspergillus niger aggregate (BFE631). The results showed that both K. thermotolerans strains evaluated have a strong influence on the expression of mycotoxin biosynthesis genes. The production of OTA can be regarded as an adaptation imposed by other stress conditions to these ochratoxigenic species. The activation of pks gene can be a cause or a consequence of a stress imposed to the ochratoxigenic specie. A viable hypothesis can be that the influence of external factors on ochratoxin biosynthesis pathway is regulated at the transcription level.