Unhairing wastewater treatment by Bacillus pumilus and Bacillus cereus

Two proteolytic bacteria Bacillus pumilus and Bacillus cereus were isolated from an aerobic tannery effluent treatment tank. Both strains were characterized and used for the treatment of unhairing wastewater during batch experiments. Chemical oxygen demand (COD), biomass production and protease activity were determined during the incubation period. The maximum COD removals were of 41 and 44% after 10 days incubation in B. cereus and B. pumilus, respectively. Optimum pH and temperature for protease and keratinase production by both strains were also investigated. Results showed that the optimum temperature and pH of protease production in the cultures of B. pumilus and B. cereus were of 30°C and 9.0, respectively. Under these optimum conditions, proteolytic activities were 283.8 and 515.8 U/mL in the cultures of B. cereus and B. pumilus, respectively. Optimum keratinase production by cultures of both bacteria occurred at the same temperature and pH of the protease production.