Comparative analysis of invertase activities in different yeast species


Thesis Type: Postgraduate

Institution Of The Thesis: Bursa Uludağ University, Fen Bilimleri Enstitüsü, Biyoloji , Turkey

Approval Date: 2003

Thesis Language: Turkish

Student: NÜKHET KAYAKENT

Supervisor: Sezai Türkel

Abstract:

Invertase enzyme, which is found in yeasts, is an industrial enzyme, and hydrolyses sucrose and raffinose. The synthesis of invertase enzyme is regulated by glucose repression and derepression mechanisms and large amount of this enzyme is secreted. In Saccharomyces cerevisiae the expression of SUC2 gene which encodes invertase enzyme was analysed well and it was shown that the nucleosoms are required for glucose repression and after derepression, certain activators are also needed for SUC2 gene transcription. It was also shown that besides glucose repression, transcription from SUC2 gene is affected by enviromental conditions like osmotic stress. It is not completely known if the synthesis of invertase enzyme in all yeast species is regulated as in S. cerevisiae or not. While some yeast species don't have any invertase enzyme, in the others invertase enzymes' reaction conditions are different from S. cerevisiae. In the yeast species Pichia angusta, Pichia farinosa and Debaryomyces hanseni which were analysed in this study invertase activity was not found. It was seen that the invertase activity of Pichia anomala is much less than the invertase activity of laboratory species of S. cerevisia. When it is compared with S. cerevisia, it was seen that derepression for invertase synthesis in P. anomala is much slower. It was also seen that invertase synthesis in P. anomala doesn't affected by osmotic stress and the duplication time of P. anomala in the growth mediums which have different carbon sources is much shorter than S. cerevisia.