Fed batch and batch submerged fermentation for alkaline protease production from mixed consortium of Pseudomonas putida and Staphylococcus aureus

First report on the production of protease through fed batch cultivation using co-culture of Pseudomonas putida and Staphylococcus aureus from a crude carbon source, banana peel. Batch production by using synthetic medium, impact of some of the process parameters on cell growth and alkaline protease activity was investigated and the optimized values were found to be inoculum size of 5 % (v/v), period of cultivation as 72 hr, incubation temperature of 40C, and initial pH of production medium as 8.0. Synthetic medium was improved with the addition of dried and ground banana peel as the main carbon source and was economized with the replacement of its nitrogen source of synthetic medium, yeast extract, by soybean meal. Further the effective concentrations were found to be 2% (w/v) banana peel and 1% (w/v) soybean meal with the alkaline protease activity of 1443.67±5.6 U/ml through batch fermentation. Mathematical models were proposed for the effect of temperature, incubation time, and pH of cultivation medium. The suitability of these proposed models was checked with ANOVA. Higher concentrations of banana peel (> 2% (w/v)) and soybean meal (> 1% (w/v)) were found to inhibitory to alkaline protease activity. This problem was overcome by shifting batch to fed batch fermentation with constant supply of standard medium of banana peel (2% (w/v)) and soybean meal (4% (w/v)) at 70hr of operation. Specific growth rate was continuously decreased due to dilution of cultivation medium while the concentration of bacterial cell mass and alkaline protease were found to increase and finally reached a constant value. Fructose which was the main carbon component of banana peel was utilized by cells and kept its value as low as 1.2 g/l. Enzyme activity in fed batch fermentation was 1.81 fold increase than batch fermentation.