Efficient media for high menaquinone-7 production: response surface methodology approach
Efficient media for high menaquinone-7 production: response surface methodology approach
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DOI：
10.1016/j.nbt.2011.07.007
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发表时间：
2011-10-01
影响因子：
5.4
通讯作者：
Dehghani, Fariba
中科院分区：
文献类型：
--
作者：
Berenjian, Aydin;Mahanama, Raja;Dehghani, Fariba
本研究的目的是评估营养素对甲基萘醌-7生产的影响，并确定实现该产品高浓度的最佳条件。将纳豆枯草芽孢杆菌在40 ℃下发酵6天。采用试验设计筛选最有效的营养素，采用中心复合面设计进行优化。最佳培养基组成为：酵母膏5%（w/v）、大豆蛋白胨18.9%（w/v）、甘油5%（w/v）、K2 0.0 6%（w/v）、HPO 4 0.0 6%（w/v）。每天在最佳发酵培养基中测量pH、细菌生长、氨基酸、甘油和甲基萘醌-7的浓度。总游离氨基酸浓度增加1.7倍，在发酵过程中。在发酵期结束时，赖氨酸和谷氨酸含量最高，而精氨酸、天冬酰胺和丝氨酸是限制性氨基酸。在发酵的第三天，甲基萘醌-7的浓度接近最终值的86%，其中细菌生长处于指数期。在此条件下，发酵培养基中作为碳源的甘油和作为氨基酸源的天冬酰胺、丝氨酸和精氨酸的浓度显著降低。甲基萘醌-7的最佳浓度与模型预测值吻合良好（96%的有效性）。发酵6天后，甲基萘醌-7的最大浓度达到62.32 +/- 0.34 mg/L;该值是文献中报告的最高浓度。
The aim of this study was to assess the effect of nutrients on the production of menaquinone-7 and determine the optimum conditions to achieve a high concentration of this product. Bacillus subtilis natto was fermented at 40 degrees C for a period of six days. Design of experiments was used for screening the most effective nutrients, and central composite face design was employed for the optimization. The optimum media consisted of 5% (w/v) yeast extract; 18.9% (w/v) soy peptone; 5% (w/v) glycerol and 0.06% (w/v) K(2)HPO(4). The pH, bacterial growth, concentrations of amino acids, glycerol and menaquinone-7 were measured at the optimum fermentation media each day. Total free amino acids concentration increased 1.7-fold during the fermentation. Lysine and glutamic acid were the most abundant whereas arginine, asparagine and serine were the limiting amino acids at the end of fermentation period. The menaquinone-7 concentration approached 86% of the final value in the third day of fermentation, where the bacteria growth was at exponential phase. At this condition the concentration of glycerol as carbon source and asparagine, serine and arginine as the amino acid sources were dramatically diminished in the fermentation media. The optimum menaquinone-7 concentration was in good agreement with the predicted value by the model (96% validity). The maximum menaquinone-7 concentration of 62.32 +/- 0.34 mg/L was achieved after six days of fermentation; this value is the highest concentration reported in the literature.