Antarctic yeasts: analysis of their freeze-thaw tolerance and production of antifreeze proteins, fatty acids and ergosterol.

BACKGROUND: Microorganisms have evolved a number of mechanisms to thrive in cold environments, including the production of antifreeze proteins, high levels of polyunsaturated fatty acids, and ergosterol. In this work, several yeast species isolated from Antarctica were analyzed with respect to their freeze-thaw tolerance and production of the three abovementioned compounds, which may also have economic importance.

RESULTS: The freeze-thaw tolerance of yeasts was widely variable among species, and a clear correlation with the production of any of the abovementioned compounds was not observed. Antifreeze proteins that were partially purified from Goffeauzyma gastrica maintained their antifreeze activities after several freeze-thaw cycles. A relatively high volumetric production of ergosterol was observed in the yeasts Vishniacozyma victoriae, G. gastrica and Leucosporidium creatinivorum, i.e., 19, 19 and 16 mg l- 1 , respectively. In addition, a high percentage of linoleic acid with respect to total fatty acids was observed in V. victoriae (10%), Wickerhamomyces anomalus (12%) and G. gastrica (13%), and a high percentage of alpha linoleic acid was observed in L. creatinivorum (3.3%).

CONCLUSIONS: Given these results, the abovementioned yeasts are good candidates to be evaluated for use in the production of antifreeze proteins, fatty acids, and ergosterol at the industrial scale.