Abstract: Bio-surfactin produced by Bacillus spp. is one kind of cyclic lipopetide with important antibiotic and biofilm-promoting func-tions,and the amount and component constitution affect its functions. In order to improve its production from Bacillus strain B006,the liquid culture medium and fermentation conditions were optimized by single-factor experiment and orthogonal experiment,and the effects of carbon source,nitrogen source,inorganic salts,and other nutrients,as well as inoculation,incubation time,liquid volume and initial pH value on surfactin production of Bacillus B006 in shake flask were investigated. The surfactin amount in fermentation broth was determined by the oil dispersing activity in the optimal tests,and its amount as well as component constitution were finally analyzed and determined by HPLC-MS method. Results showed that,the optimized culture mediums of surfactin production were as follows：beef extract 10 g/L,corn flour 15 g/L,NH₄N0₃ 3 g/L,and NaCl 3 g/L. The optimized fermentation conditions for surfactin production in shaking flask were as follows：initial pH7.0,the inoculation ratio 10%,volume in shake flask 60 mL/500 mL,and culture time 64 h. Under the optimal culture medium and fermentation conditions,the surfactin amount reached 314.73 mg /L,with an improvement of 74.88%,and the amount of surfactin components C16 and C17 increased obviously,raised by 1.64 and 8.34 times,in comparison with no optimization. In a conclusion,under optimized medium components and culture conditions,the surfactin production from Bacillus strain B006 is improved and its component constitution change. All the above results lay a foundation for surfactin production in large scale and further research in metabolic and regulation of surfactin produced by strain B006.

Key words: Bacillus substilis, surfactin amount, orthogonal experiment, oil dispersing activity