解磷巨大芽胞杆菌液体发酵的培养基优化

为得到高密度发酵的最优培养基组成，以一株分离自土壤的解磷巨大芽胞杆菌为研究对象，以发酵液OD600为判断活菌数依据，进行响应面法优化试验。首先进行单因素试验筛选培养基中的碳源、氮源、碳源浓度、氮源浓度、无机盐及无机盐浓度，得到单因素最佳值；然后利用响应面设计，通过3步试验，即部分因子试验、最陡爬坡试验和中心组合试验对培养基进行优化。结果表明：该株巨大芽胞杆菌的最佳培养基质量组成为：乳糖6 g/L，蛋白胨7.45 g/L，NaCl 5 g/L，MgSO4·7H2O 2.46 g/L，CaCl2 1.22 g/L，K2SO4 0.087 g/L。在此最优培养基条件下培养，发酵液最终活菌数达到2.0×109 cfu/mL以上。运用此培养基配方进行发酵，可为农业生产提供高密度的磷细菌菌剂。

Medium Optimization for Phosphate-solubilizing Bacteria Bacillus Megaterium in Submerged Fermentation

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.