PROTOPLAST FUSION IN PENICILLIUM FUNICULOSUM MUTANTS FOR ENHANCING DEXTRANASE PRODUCTION

ABSTRACT
 
Two induced mutant strains, obtained from the fungus Penicillium funiculosum after UV treatments, were used for protoplast fusion. These mutants (12 and 18) were selected according to their dextranase activity and stability. Seven fusants having dextranase over-yield than their parental strain were obtained. The best dextranase producing fusant (No. 2) was selected for further studies. Dextranase was purified from cell-free culture of fusant 2 by consecutive column chromatography using Q-sepharose FF, Superose 12 prep. grade 60/600 and Mono Q-FPLC. The purification was estimated by SDS-PAGE as well as isoelectric focusing. Four dextranase components (I, II, III and IV) were separated with an estimated molecular weights of 67 kDa. The pI of the all components were found to be around 3.0 as estimated by gel electrophoresis using both broad and low pI calibration protein kits. The dxetranase components showed pH and optimum temperature of 5 and 55^oC, respectively. Dextran was the sole carbon source for dextranase production by the dextranase components. The effect of the dextranase components on different types of dextrans were also studied.