Abstract:
A psychrotolerant yeast strain Mrakia robertii A2-3 isolated from cryoconites of Hamtah glacier, Himalaya, India was investigated for the production of cold tolerant endoglucanase. Optimum endoglucanase production was found at 15 degrees C with an initial pH of 5.5, and potent inducers were 1 percent w/v of xylose and KNO sub(3) and 0.1 percent w/v of NaCl. Under the optimum conditions, enzyme production was 1.81 fold higher than the un-optimized conditions. Crude enzyme was partially purified by ammonium sulphate precipitation followed by dialysis. The enzyme was purified to 2.53 fold and yield was 6.03 percent with specific activity of 17.38 U/mg and molecular weight approx 57 kDa. The K sub(m) and V sub(max) values of the partially purified enzyme were found to be 1.57 mg/ml and 142.85 U/mg, respectively. The characterization study revealed that the best temperature was 15 degrees C for activity and stability. Furthermore enzyme showed the highest activity at pH 11.0 and was stable at pH6.0. Fe sup(2+), Mn sup(2+), Na sup(2+), Cu sup(2+), Co sup(2+), Ca sup(2+) proved to be activators of endoglucanase. EDTA showed very low effect on the enzyme activity whereas it was active with Tween-80 and sodium deoxycholate. The present study successfully produced a cold-active endoglucanase with novel properties making it promising as a biocatalyst for industrial processes.
