从云南文山筛选出一株高产吲哚乙酸(indole-3-acetic acid,IAA)的烟草肠杆菌(Enterobacter tabaci)β7,在摇瓶水平上对碳源种类、氮源种类、接种量、IAA前体物质色氨酸等发酵工艺参数进行单因素实验和响应面优化,确定了最佳发酵培养基组成为:碳源半乳糖6 g/L,氮源酵母粉2 g/L,色氨酸500 mg/L。接种量5%发酵16 h条件下,发酵液中IAA质量浓度最高达到276.96 mg/L,较优化前提高了13.53%。研究了不同添加剂,包括抑菌剂、保护剂和乳化剂等对菌剂保藏条件下活菌率和IAA保留率的影响,确定最适添加剂为抑菌剂山梨酸钾、保护剂甘油、乳化剂吐温-60,在此基础上,制备菌剂在避光4 ℃保藏24 d后,活菌率达到91.10%,IAA保留率达到88.77%。
A strain of Enterobacter tabaci β7 with high yield of indole-3-acetic acid (IAA) was screened from Wenshan, Yunnan province.At the shaking flask level, single factor experiment and response surface optimization were carried out on the fermentation process parameters, such as carbon source, nitrogen source, inoculum size, IAA precursor tryptophan, and so on.The optimal fermentation medium composition was determined as follows:galactose 6 g/L, yeast powder 2 g/L, tryptophan 500 mg/L.Under the condition of fermentation with 5% inoculum for 16 h, the highest concentration of IAA in the fermentation broth reached 276.96 mg/L, which was 13.53% higher than before.The effects of different additives, including bacteriostatic agents, protective agents, and emulsifiers, on the viable bacterial rate and IAA retention rate were studied.The most suitable additives were potassium sorbate, glycerin, and Tween-60.On this basis, after the prepared bacterial agent was stored for 24 days in the dark at 4 ℃, the viable bacterial rate reached 91.10% and the IAA retention rate reached 88.77%.
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