Optimization of growth conditions for a recombinant keratinase producing bacterial strain

Abstract: A recombinant Bacillus megaterium strain with a chromosomally integrated gene kerA, expressing keratinase, was analyzed regarding action in specific environmental stresses to obtain optimum parameters necessary for bacterial growth and optimal expression of the recombinant gene.The strain was grown on chicken feathers as substrate and the degradation of feather keratin during the growth was investigated with different levels of pH, temperature and feather concentration in the broth. Two strains were analyzed, capable to grow with 575 x and 1025 x amounts of antibiotics, erythromycin, where the strain of 1025 x showed higher potential for expression. Maximum keratinolytic activity was achieved at a pH of value 8.5, at temperature of 45 °C and substrate concentration of 0.2 % (w/v). The growth rate was determined by total plate count, which indicated that there was an increasing number of colony forming units together with increasing concentration of soluble keratin. The diluted fractions did not appear to produce colonies to any significant amount. However the results for which reason the results for optimal growth conditions are guidelines for future analysis for a chromosomally recombinant Bacillus megaterium.