Comparative
analysis of glycerol metabolism in yeasts.
Annamaria Merico,
Ileana Vigentini, Carlo Spinelli, Bianca Maria Ranzi, Concetta Compagno
Fisiologia e Biochimica, Università di Milano, via Celoria 26, Milano, 20133,
Italy (annamaria.merico@unimi.it)
A fine analysis of carbon metabolism is a fundamental tool to understand the complexity of yeast physiology. Moreover a comparative analysis in different yeast species may have a special interest, also by an evolutionary point of view. In this respect glycerol metabolism is particularly intriguing, being glycerol used by cells not only as a carbon source. In fact it is also involved in the regulation of redox balance and in osmoregulation too. Many yeast species are in fact able to grow on glycerol as the sole carbon source, but the uptake systems and the pathways for its dissimilation may differ. In this work we performed a comparative analysis of glycerol metabolism in different strains of the yeast Saccharomyces cerevisiae, and of the non-conventional yeasts Kluyveromyces lactis and Zygosaccharomyces bailii. In contrast to Saccharomyces cerevisiae and Kluyveromyces lactis, in which growth on glycerol is not related to the pH of the media, Zygosaccharomyces bailii shows a strictly pH-dependent glycerol utilization. Kluyveromyces lactis strains are able to grow on glycerol in both mineral and rich media, at different rates. The ability to use glycerol as the sole carbon source by Saccharomyces cerevisiae strains, is deeply affected by the composition of the growth media. Growth is in fact severely impaired in mineral media, showing very long lag phases. This could be related to the redox status of the cells. Physiological and biochemical evidences will be showed.