engleski

Effect of Ochratoxin A on the Growth and Morphological Properties of Saccharomyces cerevisiae and Saccharomyces uvarum

Ochratoxin A (OTA) is a nephrotoxic, immunosuppressive, teratogenic, and carcinogenic mycotoxin, secondary metabolite produced by species belonging to Aspergillus and Penicillium genera, mainly A. ochraceus, A. niger, A. carbonarius, and P. verrucosum. This ubiquitous mycotoxin is a contaminant of many foodstuffs, mainly cereals but also wine. The aim of this study was to assess how concentration of OTA affects the growth and morphological properties of selected yeast strains of Saccharomyces cerevisiae and Saccharomyces uvarum. The wine yeasts were exposed to a toxin-containing medium during 168 hours at 28°C. Determinations were carried out for the following parameters: cell count and cell diameter. regardless of its concentration in medium, OTA exerted a poor effect on the growth parameters of both yeasts. Obtained results show that in both yeasts (with and without added OTA) the lenght of lag phase was 4 h, the exponentional growth occured between 4 and 24 h, after which appears stationary phase which lasted until 168 h. Ochratoxin A changed morphological characteristics of S.cerevisiae and S.uvarum primary affecting cell diameter reduction. The biggest difference in the diameter was about 20 % in both yeasts, it was observed after 24 h of inoculation for the S.cerevisiae cells grown on OTA added media and after 48 h for S.uvarum cells. Both yeast strains developed a specific response to the influence of OTA which indicates that the toxicity of OTA was low or the yeasts have adapted to the presence of the contaminant.

Ochratoxin A; wine yeasts; morphological characteristics; growth

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