Influence of thermal and osmotic pressure on the growth and viability of Candida shehatae var shehatae

Abstract

Environmental stresses can bring abrupt changes in microbes and it can affect its growth with a number of visible modifications. Although some studies emphasize on the bacterial and fungal cellular response against acute heat and mitochondrial substrate oxidative stresses, in case of yeast very few researches were conducted. Currently, Saccharomyces cerevisiae is only known yeast about their responses against different stresses. The present study has been performed to observe how the growth and budding pattern of Candida shehatae var shehatae will be influenced by high temperature (40-45°C), as well as the impact of osmotic stresses on yeast cell. To find out the critical growth temperature of C. shehatae var shehatae growth was monitored at 40 and 45°C for 72 h. Osmotic stress tolerance was observed at 32.5°C in diverse dextrose (0.04 g/l (1X), 0.12 g/l (3X), 0.2 g/l (5X), 0.28 g/l (7X), 0.36 g/l (9X)) and sucrose, that is 0.02 g/l (1X), 0.06 g/l (3X), 0.1 g/l (5X), 0.14 g/l (7X) , 0.18 g/l (9X) concentrations. The result was monitored at 600 nm at different time intervals. The viability of strains was analyzed by determination of CFU/ml. The optimal growth pattern was observed at 32.5°C and cells lose their cultivability at 45°C. Cell growth and budding were observed under high dextrose and sucrose concentrations and suppressed at 45°C. Results of the current study indicated that the critical growth temperature is 45°C and under sugar concentrations stress stimulant was also shown at that temperatures. Keywords: Candida shehatae var shehatae, dextrose, heat stress, critical growth, osmotic stress, morphological pattern.