Enhanced production of streptokinase from Streptococcus agalactiae EBL-31 by response surface methodology

Streptokinase (SK) is a fibrinolytic protein used for the treatment of cardiovascular disorders. In the present study, enhanced production of SK was achieved by determining the optimum fermentation conditions for the maximum growth of Streptococcus agalactiae EBL-31 using response surface methodology (RSM). Four process variables (pH, temperature, incubation time and inoculum size) with five levels were evaluated in 30 experimental runs. Central composite rotatable design (CCRD) was employed to predict the effect of independent variables on SK activity. The statistical evaluation by ANOVA showed that the model was fit as the effect of single factors, quadratic effects and most of the interactions among variables. The value ofR2 (0.9988) indicated the satisfactory interaction between the experimental and predicted responses. Furthermore, the model F value (902.67) and coefficient of variation (1.92) clearly showed that the model is significant (p =>0.0001). The functional activity of SK was determined by spectrophotometric analysis and maximum SK production was obtained at pH-7.0, temperature- 37.5oC, an incubation time of 36 hours and 2.5 mL inoculum size. Hence it was concluded that the optimization of culture conditions through RSM increases the production of SK by 2.01-fold. Production of SK by fermentation is an economical choice to be used for the treatment of cardiovascular diseases.