常压室温等离子体快速诱变绿色糖单孢菌筛选 木聚糖酶高产菌株及其酶学性质研究

Screening of mutants of xylanase high-producing strain of Saccharomonospora viridis by atmospheric and room tem-perature plasmas and its enzyme characterization

摘要:

【目的】利用常压室温等离子体快速诱变绿色糖单孢菌, 筛选耐热耐碱木聚糖酶高产菌株, 并对其进行酶学性质分析, 确保其适用于生物制浆漂白工艺。【方法】采用刚果红平板水解圈法结合摇瓶发酵胞外酶测定法进行菌株筛选, 并通过DNS木聚糖酶活性测定等方法对来源于不同突变株的木聚糖酶进行酶学性质分析对比。【结果】筛选出遗传稳定性良好的两株木聚糖酶高产菌株AT24和AT22-2, 以麦草浆为诱导底物的粗酶液中, 突变株AT24及AT22-2所产的木聚糖酶活性分别为512.74、552.70 U/mL, 分别为原始菌株S. v的16和17倍的。来源于突变株AT22-2的木聚糖酶的最适反应pH为9.5, 最适反应温度为90 °C, 在50 °C?90 °C温度范围内具有良好的热稳定性, 在100 °C条件下处理30 min剩余酶活仍为68%; 突变株AT24所产木聚糖酶的最适反应温度为60 °C, 最适pH为10.0, 在60 °C?80 °C的高温环境下, 突变株AT24所产的木聚糖酶具有良好的热稳定性。【结论】突变株AT22-2所产具有耐碱耐高温性质的木聚糖酶, 在应用领域尤其在纸浆造纸行业具有较大的潜在应用价值。

Abstract:

[Objective] In order to obtain an industrial strain with higher xylanase production, the original strain of Saccharomonospora viridis was mutated by atmospheric and room temperature plasmas. [Methods] The methods used to screen the mutant strain with higher xylanase production included transparent loop diameter measurement of selective medium with 2% beech-wood xylan and shaking flask fermentation. [Results] It has been demonstrated that both mutants AT22-2 and AT24 maintain good genetic stability. The enzyme activity in the fermentation liquor of AT22-2 and AT24 at 7 d reached 552.70 U/mL and 512.74 U/mL, which were 17 and 16 times higher than that of the original strain, respectively. Furthermore, the op-timum pH and temperature values for xylanase activity of AT22-2 were pH 9.5 and 90 °C, re-spectively, being stable within a temperature range of 50 °C?90 °C, and showing high thermo-stability at 100 °C for the duration of 30 min. In addition, for another mutant AT24, the opti-mum pH and temperature values for xylanase activity were pH 10.0 and 60 °C, with a stability within a temperature range of 60 °C?80 °C. [Conclusion] The xylanase with thermostability and alkali-tolerance of mutant AT22-2 is a potential candidate for future use in biotechnologi-cal applications particularly in the pulp and paper industry.