Abstract

Bhargavi Moturi* and M. A. Singara Charya

The decolourisation efficiency of the wild fungal strain Mucor mucedo was investigated by the treatment with physical mutagen ultraviolet radiation (UV) and chemical mutagens [ethyl methyl sulfonate (EMS), diethyl sulfonate (DES) and colchicines]. The mutants that were exposed to 12 and 15 min UV radiation showed reduction in extension and branching of hyphae. EMS at concentrations of 100 and 150 mg inhibited the germination of spores in M. mucedo. Surprisingly, at concentrations of 100 and 150 mg DES, spores were converted to yeast like cells which produced buds instead of hyphae. Colchicine at higher concentrations abolished the germ tube and hyphal elongation. There was stimulatory effect on growth at lower concentrations only. With respect to enzyme productions and decolourisation activity, there was increase in protease (1.48 U/ml) and peroxidase (1000 U/ml) production in Mucor mucedo when exposed to 9 min UV radiation and showed maximum decolourisation activity of crystal violet (90%) and malachite green (70%). There was an increase in the peroxidase enzyme (1200 U/ml) production at 50 mg concentration relating to the maximum decolourisation activity of crystal violet (90%) and malachite green (71%). Also, there was a decrease in the production of all enzymes in Mucor mucedo when treated with different concentrations of DES and so, there was no improvement in decolourisation activity. There was an increase in protease (1.86 U/ml) and peroxidase (1000 U/ml) production only at 10 mg concentration of colchicine proving that the higher enzymatic secretions were responsible for the decolourisation efficiency of 89% in crystal violet and 74% in malachite green. The wild strain isolated from dye effluent amended soils when exposed to different physical and chemical mutagens showed improvement in the decolourisation of crystal violet and malachite green except in the case of DES.