γ-聚谷氨酸的发酵优化及其对辣椒生长的影响

采用实验室分离的一株高产 γ-聚谷氨酸（γ-PGA）枯草芽孢杆菌发酵生产 γ-聚谷氨酸。利用单因素优化实验选择最佳碳源、氮源及发酵前体，响应面分析法Box-Behnken。实验结果表明最佳发酵培养基配方为蔗糖60.39 g /L、硫酸铵6.00 g /L、谷氨酸钠93.27 g /L，γ-PGA产量达到70.285 g/L。将发酵提纯后获得的产品与尿素混合制备成叶面肥对辣椒进行喷施，辣椒的株高、茎粗、挂果数、果重以及叶绿素含量等显著增加，喷施10 g/L 尿素 + 0.6 g/L γ-PGA增产效果最佳，γ-PGA复合肥料的生物可降解性、环境友好性和保肥增效特性有利于农业的可持续发展。

Fermentation Optimization of Gamma-Polyglutamic Acid and Its Effect on Grow of Pepper

The Bacillus subtilis highly yielding γ-polyglutamic acid （γ-PGA） separated in the laboratory was fermented to produce γ-polyglutamic acid. The single factor optimal experiment was used to optimize carbon source， nitrogen source and precursor of fermentation. The result of response surface methodology experiment show the optimal formula of fermentation medium is sucrose of 60.39 g/L， ammonium sulfate of 6.00 g/L and sodium glutamate of 93.27 g/L， with which the output of γ-PGA increases from 7.253 g/L to 70.285 g/L. The product obtained by fermentation and purification was mixed with carbamide to prepare foliar fertilizer， which was then sprayed to the pepper plant. It was found that the plant height， stem diameter， number of fruits， fruit weight and chlorophyll content of pepper increase significantly. Spraying carbamide of 10 g/L + γ-PGA of 0.6 g/L can produce the best yield-increasing effect. Moreover， the γ-PGA compound fertilizer is beneficial to the sustainable development of agriculture with biodegradability， environmental friendliness and nutrient- preserving capability.