Farklı maya türlerinde stres koşullarında invertaz enzim aktivitesi ve ilgili gen kontrollerinin belirlenmesi

Biomass increase resulting from the increased growth rate is largely depends on the carbon source in the growth media. Growth of yeast species especially Saccharomyces cerevisiae is closely related to the uptake and effective utilization of carbon sources in growth media. Utilization of sucrose is solely depends on the extra cellular enzyme invertase which is expressed from SUC2 gene in Saccharomyces cerevisiae and INV1 gene of Pichia anomala. In this research Pichia farinosa, Pichia anomala, Pichia jadini, Candida milleri and Saccharomycese cerevisiae yeast species were grown on different carbon sources, and their invertase activities were determined at different stress conditions. Saccharomyces. cerevisiae were used as a control in our research. Pichia farinosa did not show invertase activity in all stages of growth and at different temperatures and pHs. The enzyme activity of Pichia anomala was controlled by glucose repression, in both logarithmic and stationary stages of growth. At different temperatures and pHs, invertase activity of enzyme was still controlled by glucose signalling. Pichia jadini and Candida milleri showed the highest invertase activity that was not affected by glucose repression and stresses at 2% glucose. Our results showed that temperatures between 25°C and 30°C were an optimum temperature and pHs between 5.0 and 6.0 were a suitable pH for growth and maximum invertase activity of Pichia anomala, Pichia jadini and Candida milleri. Invertase enzyme activities of Pichia anomala and Saccharomyces cerevisiae at short-term derepression condition was greater than long-term derepression condition. Key Words: Pichia sp., Candida sp., Invertase, Heat Stress, Acidity, Glucose Repression