关键词: 巨大芽胞杆菌；培养基；响应面法；优化

Abstract:

Response surface optimized experiment was carried out to gain a best culture medium with high density zymic. This experiment tool a strain of phosphate-solubilizing bacteria Bacillus megaterium isolated from soil as research objective, and OD600 of the broth as a standard to judge the number of viable cells. Firstly, single element experiment was conducted to screen the carbon source, nitrogen source, carbon source concentration, nitrogen source concentration, inorganic salts and its concentration from the medium, and achieve the best value of single element. Then 3 steps experiments namely fractional factorial design (FFD), steepest ascent experiment and central composite design (CCD) were conducted to optimize the culture medium by using response surface design. The results showed that the optimal culture medium composition included: lactose 6 g/L, peptone 7.45 g/L, NaCl of 5 g/L, MgSO4·7H2O 2.46 g/L, CaCl2 1.22 g/L, and K2SO4 0.087 g/L. Under this optimal culture medium, the number of viable cells of Bacillus megaterium in ferment fluid could reach over 2.0×109 cfu/mL. Fermentation of medium by this formulation could provide high density phosphate-solubilizing bacterial fertilizer for agriculture production.

Key words: Bacillus megaterium, medium, response surface methodology, optimization