EFFECT OF UV RAYS AND CHEMICALS ON CELLULASE PRODUCTION OF ASPERGILLUS NIGER IN SUBMERGED FERMENTATION USING RICE HUSK AS SUBSTRATE

Abstract

Cellulases are employed in variety of sectors such as paper, textile, pharmaceuticals, food, leather and detergent.
Microorganisms secrete cellulases while growing on cellulosic materials that have been proved effective in various
industries. The efficiency of microbial cellulase production can be improved by treating microbes with different
mutagens. In the present study Aspergillus niger spores were exposed to UV radiation, ethidium bromide, and nitrous
acid and cellulase activity was assessed after each treatment. Wild strain Aspergillus niger was capable toproduce 0.18
IU/ml/min CMC-ase and 0.27 IU/ml/min FP-ase activities. Short-wave UV light (254 nm) exposure for 30 minutes
resulted in a 39% increase in CMC-ase and 33% increase in FP-ase activities, while long-wave UV light (366 nm)
exposure resulted in a 33% increase in both CMC-ase and FP-ase activities, compared to the wild strain. CMC-ase
and FP-ase activities after 0.25 mg ml-1 ethidium bromide treatment increased about 22% and 16% respectively than
the wild strain whereas 0.25 M nitrous acid treatment gave 100% increase in CMC-ase activity and a 48% increase in
FP-ase activities. In recent research, nitrous acid has been found more effective in raising cellulase activity to a greater
extent as compared to UV exposure and ethidium bromide treatment. This study suggests that mutagenesis of fungal
strain could provide a new choice for the processing of bioresources in the future to produce enhanced cellulase
production.