Bacillus Cereus GD 55 Strain Improvement by Physical and Chemical Mutagenesis for Enhanced Production of Fibrinolytic Protease

Abstract

This work has been undertaken to enhance the production of industrially important fibrinolytic protease by subjecting indigenous fibrinolytic protease producing Bacillus cereus to strain improvement by random mutagenesis using ultra-violet (UV) irradiation, ethyl methane sulfonate (EMS) and ethidium bromide treatment. Mutants were screened on the basis of enzyme assay by spectrophotometer using folin’s phenol reagent. Ethyl methane sulfonate (EMS) and ethidium bromide treated Bacillus cereus GD 55 was proved to be the best for optimum production of fibrinolytic protease. The effect of different production parameters such as carbon source, inoculum sizes, pH, temperature, nitrogen source (inorganic and organic) and incubation time on fibrinolytic protease production by the mutated bacterial strain was studied. The enzyme production was assayed in submerged fermentation (SmF) condition. The maximum fibrinolytic protease production was observed with fructose 1% (18.60 ± 0.62 U/ml), inoculum size level 2% (22.10 ± 0.80 U/ml), pH 8.0 (28.65 ± 0.41 U/ml), temperature 35°C (28.68 ± 0.19 U/ml), NH4NO3 1% (34.24 ± 0.12 U/ml), peptone 1% (35.68 ± 0.27 U/ml) and incubation time 48 hours (38.92 ± 0.56 U/ml) in the production medium. EMS&EB-15 mutant strains were found to produce 2-4 fold more enzyme. Thus these findings have more impact on enzyme economy for biotechnological applications of microbial fibrinolytic proteases.