Effect of physiological factors on production of cellulolytic enzymes by Rhizoctonia bataticola

Abstract

Cellulose, an abundant carbohydrate, forms an integral part of the plant cell walls and provides structural integrity. Ability of any pathogenic fungus to degrade it depends largely on the extent of cellulolytic enzymes produced by a fungus. Therefore, present in vitro study was conducted to assess the effect of five each carbon and nitrogen sources on production of cellulolytic enzymes and growth of Rhizoctonia bataticola isolates the dry root rot pathogen of soybean. The results revealed that cellulolytic enzyme activity (µg of d-glucose/ml) of the 20 isolates of R. bataticola was strongly influenced and varied with the sources of carbon and nitrogen tested. Among five carbon sources tested, the cellulolytic enzyme activity was highest with Carboxy methyl cellulose (CMC) in the range of 0.629–1.286 µg, followed by Glucose (0.589–0.996 µg), Sucrose (0.549–0.961 µg), Starch (0.199–0.797 µg) and Pectin (0.152–0.293 µg) compared to control (0.107–0.187 µg). Similarly, all five nitrogen sources tested exhibited a wide range of cellulolytic enzyme activity among the test isolates. However, it was highest with Ammonium chloride (0.196–0.420 µg), followed by Potassium nitrate (0.170–0.425 µg), Glutamic acid (0.118–0.174 µg), Glutamine (0.109–0.171 µg) and Urea (0.100–0.167 µg), compared to control (0.080–0.107 µg).Various temperature regimes and pH of CMC broth medium also influenced the growth (mycelium dry weight) of the test isolates of R. bataticola and their cellulolytic enzyme activity. However, the temperature of 30 °C and 6.0 pH where found to be optimum.