Temperature gradient incubator for the study of alterations occurring with fatty acids of Saccharomyces cerevisiae when approaching extreme growth temperatures

Abstract

On lowering the temperature from 35 to 10°C, Saccharomyces cerevisiae shortens the fatty acid chain length by increasing palmitoleic acid content in relation to oleic acid whereas fatty acid unsaturation remains unaltered. The temperature gradient incubator was used to study whether these trends are also maintained on approaching extreme growth temperatures at 0.2–0.3 centigrade degrees intervals. As a result, on decreasing the growth temperature towards the lower growth temperature extreme at 2.6°C, the yeast first was found to lose its ability to shorten the fatty acid chain length between 6.5 to 3.9°C, and thereafter disturbances in fatty acid unsaturation were observed. Upon feeding palmitoleic and oleic acids to the medium, S. cerevisiae seemed to lose increasingly its ability to incorporate palmitoleic acid into lipids when lowering the temperature from 6.5 to 3.9°C, and then towards 2.6°C the desaturation of monoenes. Further, when the growth temperature increased towards the upper extreme at 39.3°C, disturbances in the fatty acid chain length and unsaturation were observed, which possibly were due to defects in the incorporation of oleic acid into lipids. The phenomena observed are repeatable, may not be related to factors such as changes in the oxygen solubility and consequently desaturation efficiency, or to the decreasing growth rate on lowering the temperature. Therefore, the temperature gradient incubator turned out to be appropriate for studies on temperature-dependent phenomena occurring in fatty acids only few centigrade degrees before cessation of growth at extremes.