活性氧胁迫促进枯草芽孢杆菌WSHDZ-01过量合成过氧化氢酶

Overproduction of catalase by oxidative stress on Bacillus subtilis WSHDZ-01

研究了乙醇和H2O2胁迫对芽孢杆菌(Bacillussp.)WSHDZ-01过量合成过氧化氢酶(Catalase,简称CAT)的影响。在Bacillussp.WSHDZ-01培养体系中添加2.0%(V/V)乙醇,胞内过氧化氢酶酶活达到11151U/mL,是对照组的2.5倍。而在培养体系中添加0.3%(V/V)H2O2,则使胞内过氧化氢酶不断分泌到胞外,胞外酶占总酶活比率增加至27%。基于上述发现,分别以不添加胁迫物(a)、乙醇胁迫(b)、H2O2胁迫(c)为对照,在培养体系中维持持续的乙醇和H2O2胁迫,结果表明:1)胞外酶比例达到82.5%;2)发酵周期缩短为42h,比对照a延长了6h,比对照b和c分别缩短了8h和6h;3)生产强度达到470U/(mL·h),比对照a提高了18.6%,为过氧化氢酶工业化生产奠定了基础。

We studied the overproduction of catalase （CAT） by Bacillus sp.WSHDZ-01 by oxidative stress via the feeding of ethanol and the pulse addition of H202. By adding 2.0% （V/V） ethanol to the culture broth, the intracellular CAT activity reached 11 151 U/mL, which was 2.5 times than that of the control （4 450 U/mL in flask）. By adding 0.3% （V/V） H202, more extracellular CAT secreted to the culture broth, and the ratio of extracellular CAT to the total CAT increased to 27%. Based on these results, an oxidative stress strategy combining the ethanol feeding and the pulse addition of H202 was developed. With this strategy, the ratio of extracellular CAT to the total CAT reached 82.5%, increased by 18.6% than that of the control （without ethanol and H202 addition）. CAT production increased to 28 990 U/mL, which was 95.5% higher than the control （14 830 U/mL in 3 L fermentor）. The fermentation time decreased to 42 h, which was much shorter than that of adding ethanol or H202, and CAT productivity reached 470 U/（mL.h） while the control achieved 396.4 U/（mL.h）.