INVESTIGADORES
CHULZE Sofia Noemi
congresos y reuniones científicas
Título:
Effect of Kluyveromyces thermotolernas strains on pks gene expression and OTA production
Autor/es:
PONSONE, M.L; SCHMIDT ,M; GEISEN, R; CHULZE, S
Lugar:
Mendoza
Reunión:
Congreso; Strategies to reduce the impact of mycotoxins in LatinAmerica in a global context; 2011
Institución organizadora:
UNRC, ISM, Mycored
Resumen:
Ochratoxin A (OTA) is one of the most important mycotoxins of concern for human and animal health. OTA has been shown to have nephrotoxic, immunotoxic, genotoxic, neurotoxic and teratogenic properties. The IARC has classified this toxin as a possible human carcinogen, group 2B. It is produced by species within Aspergillus section Nigri, Penicillium verrucosum, Penicillium nordicum and Aspergillus ochraceus that predominantly colonize cereals, coffee, cocoa and grapes. P. verrucosum and P. nordicum are more important in cool damp conditions of northern Europe while A. ochraceus in warmer climatic regions of the world. Grapes and their derived products as grape juice, dry vine fruits and wine, are frequently contaminated with this toxin. Prevention of the OTA-producing fungi growth is the most effective strategy for controlling the entry of this mycotoxin in the food and feed chains. The development of resistance to fungicides to major plant pathogens and the public concern over pesticide residues in food and the environment have increased the interest in alternative tools for disease control. In previous studies was 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 paterns of the pks enzyme,  one of the key enzyme in the OTA biosynthetic  pathway. The aim of this work was to determine if the potential biocontrol agents can affect the OTA pks expression by two Penicillium species, Penicillium nordicum BFE487 and Penicillium verrucosum BFE808. Growth and ochratoxin A production by the fungal strains at the phenotypic and molecular level were monitored in relation to Penicillium verrucosum BFE 808 and Penicillum nordicum BFE 487. Expression of the otapksPV and otapksPN genes was measured by real-time PCR and the OTA produced via HPLC. The results showed that there was a clear correlation between the expression of mycotoxin biosynthetic genes and the phenotypic production of the OTA. Obviously the external growth parameters moderate mycotoxin biosynthesis via their influence on gene transcription. Based on the results presented here, K. thermotolerans strains have a strong influence on the expression of mycotoxin biosynthesis genes. Taken together, the results showed that the production of mycotoxins can be regarded as an adaptation to imposed abiotic and other stress conditions by these mycotoxigenic species. If the activation of mycotoxin biosynthesis is the cause or the consequence of a stress reaction cannot yet be concluded. It appears that the influence of external factors on ochratoxin biosynthesis is indeed mediated by regulation of transcription.