西索米星生产菌株的诱变选育及工艺优化

Mutation Breeding of Sisomicin Producing Strain and Optimization of Fermentation Process

摘要:

利用原生质体常压室温等离子体（ARTP）诱变方法选育西索米星高产菌株，经诱变筛选获得一株高产菌株I4-10，其西索米星的生物效价达到1 389 U/mL，较原始菌株提高了35.4%。通过对高产菌株I4-10进行碳源、氮源优化，确定可溶性淀粉和牛肉粉是突变菌株I4-10的最适碳源和氮源。进一步采用响应面实验设计方法优化发酵培养基，结果表明黄豆饼粉和DL-蛋氨酸的添加量为显著影响因素，经优化其最适添加质量浓度分别为32.78 g/L和1.75 g/L。在此最适工艺下，西索米星的生物效价提高至1 849 U/mL，较原始菌株提高了80%。最后对原始菌及高产突变株中西索米星代谢途径及菌株生长相关的关键酶进行转录水平比较分析，初步解析了突变菌株I4-10高产西索米星的机制。

Abstract:

The high-yielding strain of sisomicin was selected by protoplast normal pressure and room temperature plasma mutagenesis. A high-yielding strain I4-10 was obtained through mutagenesis and the biological titer of sisomicin reached 1 389 U/mL, which was 35.4% higher than the original strain. By optimizing the carbon source and nitrogen source of the high-yielding strain I4-10, it was determined that the soluble starch and beef meal were the most suitable carbon and nitrogen sources for the mutant strain I4-10. The response surface method was further used to optimize the fermentation medium. Results showed that the mass concentrations of soybean meal and DL-methionine were significant influencing factors, and the optimal addition concentrations were 32.78 g/L and 1.75 g/L, respectively. Under this optimal condition, the biological titer of sisomicin was increased to 1 849 U/mL, which was 80% higher compared to the original strain. Finally, the authors compared the transcription level of the key enzymes related to the metabolic pathway of sisomicin, the growth of the high-yielding mutant strain and the strain in the starting bacteria, and preliminarily analyzed the high production mechanism of sisomicin by the mutant strain I4-10.