Medium optimization and production of secreted Renilla luciferase in Bacillus subtilis by fed-batch fermentation

Luciferase of the soft coral Renilla reniformis (Rluc) has found a multitude of potential applications. However, its production in a secreted form has been solely performed in mammalian cells. In this work, a high production of secreted Rluc was approached in Bacillus subtilis by implementing the fermentation strategy. First, three critical medium components among others were selected by the Plackett-Burman design. Followed by the Box-Behnken design, the medium formulation was optimized and composed of 1.17% glucose, 2.27% yeast extract, and 0.55% glutamate. With the optimum medium, the shake-flask culture of the producer strain was carried out to secret Rluc with the yield of 55 mg/L. Finally, the production scheme was scaled up using a 5-L jar fermenter operated in a fed-batch mode. By controlling the operational condition, the feeding solution was pumped in an impulse mode to the culture. As a consequence, the production of Rluc reaching 500 mg/L was obtained after fermentation for 27 h. (C) 2010 Elsevier B.V. All rights reserved.