Application of response surface methodology in medium optimization for protease production by the new strain of Serratia marcescens SB08

For production of protease by a new strain, Serratia marcescens SB08, optimization of the fermentation medium and environmental conditions, were carried out by applying factorial design and response surface methodology. The results of factorial design showed that pH, agitation, incubation time and yeast extract were the key factors affecting protease production. The optimal cultural conditions for protease production obtained with response surface methodology were pH 6.0, agitation 100 rpm, incubation time 51.0 h and yeast extract 3.0 g/l. This model was also validated by repeating the experiments under the optimized conditions, which resulted in the maximum protease production of 281.23 U/ml (Predicted response 275.66 U/ml), thus proving the validity of the model. Unexplored Serratia marcescens SB08 strain isolated from enteric gut of sulphur butterfly (Kricogonia lyside) was taken up for this study. This study demonstrates the ability of the new strain, Serratia marcescens SB08, for protease production and also that smaller and less time consuming statistical experimental designs are adequate for the optimization of fermentation processes for maximum protease production.