Breeding and characteristics of the high efficient biodemulsifier-producing bacteria by mutagenesis

To improve demulsifying property, the original biodemulsifier-producing bacterium, Bacillus mojavensis XH1, was mutated and bred by the combined treatment method using UV irradiation and nitrosoguanidine (NTG). A high efficient biodemulsifier-producing mutant XN5 with the better stability was obtained after continuous passages. The optimal cultural conditions were as follows: the mixture of 10 g/L glucose and 4% liquid paraffin is the carbon source, the mixture of 4.0 g/L NH ₄Cl and 1.0 g/L yeast extract is nitrogen source, pH=6.5, the rotating rate is 140 r/min and the incubated time is 24 h. The 12 h and 24 h demulsification ratios of the mutant XN5 were 94.17% and 98.67%, which were 64.81% and 15.12% higher than that of the original strain XH1, respectively.