产IAA菌株的UV和DES诱变筛选及培养条件优化

为了得到高产吲哚-3-乙酸(IAA)菌株,采用紫外(UV)诱变和硫酸二乙酯(DES)诱变的方法,对从烟草根际土壤中分离得到的一株产IAA并具有溶有机磷性状的促生菌进行诱变选育,并对获得的目标菌株的发酵培养条件进行正交优化。结果表明,菌株经UV诱变和DES诱变均能有效提高其IAA产量。诱变条件为 UV(15 W,30 cm)照射1 min或2 mg·mL^-1 DES处理30 min时,得到1株高产IAA的菌株UV19,其IAA产量为33.77 mg·L^-1,是出发菌株产量的299.48%。菌株UV19经10代继代,其产IAA能力和溶有机磷性状稳定遗传。菌株UV19产IAA培养发酵优化条件为10%装瓶量、初始pH值8、培养温度25℃、接种量3%、培养时间96 h、含500 mg·L^-1色氨酸的LB培养基,优化后IAA产量高达75.47 mg·L^-1,为优化前的2.23倍。本研究结果为菌肥及生物法生产IAA提供了基础材料及技术方案。

Screening of IAA-Producing Strains by UV and DES Mutagenesis and Optimization of Culture Conditions

In order to obtain strains with high yield of IAA, a growth-promoting strain which was isolated from the tobacco rhizosphere soil with the ability of producing IAA and solubilizing organic-phosphorus, was mutagenized by ultraviolet and diethyl sulfate mutagenesis. Meanwhile, the fermentation conditions of the target strain were optimized by orthogonal design. The results showed that the mutagenesis by UV and diethyl sulfate could effectively increase the yield of IAA. The mutagenic conditions are irradiation with UV (15 W, 30 cm) for 1 minute or treatment with 2 mg·mL^-1 DES for 30 min. As a result, a strain UV19 with high IAA yield was obtained. And its IAA yield was 33.77 mg·L^-1, which was 299.48% of that of the initial strain. After 10 generations of subculture, the abilities of IAA-producing production and soluble organophosphorus traits of the strain were stably hereditary. The optimum conditions for IAA fermentation were as follows: 10% liquid loading, initial pH value 8.0, cultivated at 25℃ for 96 h with 3% inoculation concentration in LB medium containing 500 mg·mL^-1 tryptophan. The yield of IAA after optimization was as high as 75.47 mg·L^-1, which was 2.23 times of that before optimization. The research results provide basic materials and test methods for IAA production by bacterial fertilizer and biological method.