Optimization of Fermentation Conditions for Bacillus subtilis and Its Demulsification Efficiency

Growth and de-emulsification efficiency of Bacillus subtilis under different carbon and nitrogen sources were investigated. The fermentation conditions were also optimized with orthogonal tests. The results showed that medium containing glucose as sole carbon source and compound medium containing glucose and liquid paraffin as carbon sources could enhance the fermentation production of the Bacillus subtilis. Higher de-emulsification efficiency was obtain with medium utilized glucose as sole carbon source, compound medium utilizes glucose and gasoline as carbon source as well as medium utilized ammonium nitrate and yeast extract as nitrogen sources. The orthogonal tests showed that the incubation temperature was the most influential factor for the fermentation production of the Bacillus subtilis. The optimal combination for fementation was as follows: incubation temperature 25°C, shaker revolution 140 r/min, pH 7.0, inoculum concentration 6 mL and incubation time 24 h. The most influential factor for the de-emulsification efficiency of the fermentation products of the Bacillus subtilis’s fermentation products was the shaker revolution. The optimal combination for demulsification efficiency was as follows: incubation temperature 25°C, shaker revolution 140 r/min, pH 7.0 and incubation time 24 h.