高产几丁质酶菌株的诱变选育及发酵条件的优化

以粘质沙雷氏菌G3-1为出发菌株,通过紫外-LiCl和微波-LiCl两轮复合诱变,得到一株产酶能力高且遗传稳定的突变株GF-21,通过单因素实验和正交实验对突变株GF-21的发酵培养基和发酵条件进行优化。结果表明,最优发酵培养基成分为:乳糖6 g/L,尿素10 g/L,KCl 1.0 mmol/L,NaCl 5 g/L,胶体几丁质10 g/L,此时,几丁质酶活力为4.73 U/mL,比优化前提高了109.3%,较出发菌株提高了470%;最优发酵条件为:培养基初始pH9.0,温度30 ℃,摇床转速220 r/min,接种龄5 h,接种量10%。本文为几丁质酶的生产应用奠定了良好的基础。

Yield improvement in a chitinase-producing strain by mutation breeding and optimization of fermentation conditions

A mutant strain GF-21with high yield and stable inheritance was obtained by double round mutagenesis of ultraviolet-LiCl and microwave-LiCl using Serratia marcescens G3-1 as original strain. The fermentation conditions of GF-21 were investigated using single factor and orthogonal experiment. The result showed that the optimal fermentation medium contained 6 g/L lactose, 10 g/L urea, 1.0 mmol/L KCl and 5 g/L NaCl, 10 g/L colloidal chitin. Under the optimal fermentation medium condition, the chitinase activity was 4.73 U/mL which was 1.09-fold higher than that before optimization and was 4.7-fold higher than original strain. The optimal fermentation conditions were as follows:the initial pH9.0, the temperature 30℃, the shaking speed 220 r/min, the inoculation age 5 h, the inoculum size 10%. The result provided a theoretical foundation for chitinase applications.