Effects of temperature and salts on growth of halotolerant Debaryomyces nepalensis NCYC 3413

The effect of temperature and salts on the growth of halotolerant yeast, Debaryomyces nepalensis was studied by growing cells in shake flask on rotary shaker and cell growth was measured. Specific growth rate (μ) of D. nepalensis increased with increase in temperature from 15 to 35°C and then decreased with increase in temperature beyond 35°C when grown in presence and absence of different salts. At 40°C, both NaCl and KCl at 1.0 M concentration enhanced the specific growth rate. D. nepalensis showed synergistic effect on thermal and salt stress when grown at 35-40°C (0.5 M NaCl) and 30-40°C (0.5 and 1.0 M KCl). The organism was able to revert its specific growth rate when temperature was shifted from 20°C to its optimum temperature for growth (30°C) only in the presence of salts, which was not observed in the absence of salts. However, the same phenomenon was not observed when the temperature was shifted from 40 to 30°C. Decrease in activation energy was observed for growth at salt concentration beyond 0.5 M of NaCl and KCl. © 2008 Academic Journals Inc.