高产吲哚乙酸菌株的筛选、鉴定及其发酵特性

Screening and identification of a high-IAA-yield microbial strain and its fermentation characteristics

摘要:

微生物发酵法生产吲哚乙酸（IAA）具有条件温和、能耗低、不使用有毒有害物质、环境污染小等优点。从蔬菜根际土壤中筛选出一株产IAA能力较强的菌株FX-02，通过形态学、生理生化特征及分子生物学鉴定，将该菌株鉴定为霍氏肠杆菌（Enterobacter hormaechei）。对FX-02发酵产生IAA特性进行了研究，结果表明, FX-02生物合成IAA的途径属于色氨酸依赖型。FX-02合成IAA的适宜色氨酸浓度为10.0 g/L。FX-02产IAA的最佳碳、氮源及无机盐分别为甘油、蛋白胨和氯化钙。当发酵培养基为甘油 10.0 g/L、蛋白胨10.0 g/L、色氨酸 10.0 g/L、硫酸镁1.5 g/L、磷酸氢二钾1.5 g/L时，30 ℃、180 r/min 振荡培养72 h，FX-02的IAA产量达到达到较高水平.

Abstract:

Indole-3-acetic acid (IAA) production by microbial fermentation has some advantages such as mild reaction conditions, low energy consumption, no employment of toxic and harmful substances, and low environmental pollution. A bacterial strain FX-02 with higher producing IAA ability was isolated and screened from the vegetable rhizosphere soils, and was identified as Enterobacter hormaechei by morphology, physiological and biochemical characteristics, and molecular biology. The fermentation characteristics of FX-02 for producing IAA were studied in this work. The results showed that the IAA biosynthetic pathway of FX-02 belonged to tryptophan-dependent type. The optimal concentration of tryptophan for FX-02 to synthesize IAA was 10.0 g/L, which also indicated that the tolerant concentration of FX-02 to tryptophan was high, in other words, it had very strong transformation ability of tryptophan to IAA. The best carbon and nitrogen sources and mineral salt for FX-02 to produce IAA were glycerol, peptone and calcium chloride, respectively. When the cultural medium (glycerol 10.0 g/L, peptone 10.0 g/L, tryptophan 10.0 g/L, MgSO4 1.5 g/L and K2HPO4 1.5 g/L) was used, and FX-02 was incubated at 30°C in a shaker at 180 r/min for 72 h, the IAA yield of FX-02 was higher.