Fed-batch fermentation of Bacillus sp. L2 for alkaline protease production using different feeding strategies

In this study, fed-batch fermentation of Bacillus sp. L2 for alkaline protease production using different feeding strategies was investigated. Three feeding strategies of constant rate and linear feeding with negative and positive slop were applied and protease activity, cell density, pH variation and substrate utilization measured. The results indicated that the alkaline protease was highly produced a few hours after glucose completely consumed. However, feeding of mineral salts and yeast extract induce the protease production. The alkaline protease was highly produced during constant rate feeding without glucose in respect to linear feeding. The maximum protease production in fedbatch culture by the optimized level of feeding composition and choosing constant rate feeding was 2430 U ml-1. Therefore it was increased up to 35% compared to 1800 U ml-1 during batch culture. Under this condition, yield and productivity were increased to 121500 U g-1 and 71470 U l-1 h-1, respectively in comparison with 90000 U g-1 and 64285 U l-1 h-1 during batch fermentation.

Keywords:

alkaline protease , Bacillus , fed-batch , constant rate feeding , linear feeding