响应面法优化唾液链球菌嗜热亚种增殖培养基

采用响应面方法对唾液链球菌嗜热亚种增殖培养基进行了优化。以MRS培养基作为基础培养基,采用Plackett-Burman(PB)设计法,对12种乳酸菌生长促进因子以及培养基的初始pH等13个因素对唾液链球菌嗜热亚种STX2生长的影响进行评价。筛选出CaCl2与豆粕水解液为STX2的生长强化因子,且培养基的初始pH值也是影响该菌体生长的关键因子,而其他物质对STX2增菌量的影响不显著。然后用旋转中心组合设计及响应面分析法确定强化因子的最佳浓度以及最佳的培养基初始pH值。在优化培养基中,STX2的菌体浓度达到6·8×108cfu/mL,比优化前的1·5×108cfu/mL提高了4·5倍。

Optimization of A Culture Medium for Cell Multiplication of Streptococcus sativarius subsp thermophilus STX2 Using Response Surface Methodology

Response surface method was used to optimize the MRS-based enrichment medium of S. sativarius subsp thermophilus STX2. The influence of twelve additives and the initial pH of the media were evaluated using a Plackett-Burman design. Our results showed that CaCl_2, defatted soybean hydrolyzate and the initial pH of the media were the main factors while the other additives had no significant effect on the cell multiplication of STX2. The central composite rotatable design and response surface analysis were then used to determine the optimal levels of the main factors. The optimized medium were:MRS supplemented with 1.12 g/L CaCl_2 and 11.88mL/L defatted soybean hydrolyzate,and the initial pH of the media was 7.18. STX2 concentration increased from 1.5×10~8 cfu/mL to 6.8×10~8 cfu/mL using the optimized medium.