EXPERIMENTAL DESIGN FOR SIMULTANEOUS PRODUCTION OF PHB, MESOPHILIC PROTEASES AND LIPASES

Bacillus species such as Bacillus subtilis, Bacillus pumilus and Bacillus thuringiensis are known to produce PHB, proteases and lipases. This study employs the Plackett-Burman and Box-Behnken experimental design with the application of Excel solver for optimized production of PHB, proteases and lipases using Bacillus mixed culture. The statistical analysis of the results proved an insignificant relationship between the media compositions and the responses. The results clearly proved a competition between the production of PHB, Proteases and Lipases. Meanwhile a systematic experimental design succeeded in minimizing this competition. The maximum production of PHB, proteases and lipases gained were 16.48 g/1/48 hr, 534 Units/ml/48 hr and 22.56 Units/m1/48 hr respectively. The strategies used in this study are recommended for simultaneous production of PHB, proteases, and to some extend lipases.