Kreiner M, McNeil B, Harvey L M
Strathclyde Fermentation Centre, Department of Bioscience & Biotechnology, University of Strathclyde, 204 George Street, Glasgow G1 1XW, United Kingdom.
Biotechnol Bioeng. 2000 Dec 20;70(6):662-9. doi: 10.1002/1097-0290(20001220)70:6<662::aid-bit8>3.0.co;2-5.
A recombinant strain of Aspergillus niger (B1-D), engineered to produce the marker protein hen egg white lysozyme, was investigated with regard to its susceptibility to "oxidative stress" in submerged culture in bioreactor systems. The culture response to oxidative stress, produced either by addition of exogenous hydrogen peroxide or by high-dissolved oxygen tensions, was examined in terms of the activities of two key defensive enzymes: catalase (CAT) and superoxide dismutase (SOD). Batch cultures in the bioreactor were generally found to have maximum specific activities of CAT and SOD (Umg x protein(-1)) in the stationary/early-decline phase. Continuous addition of H2O2 (16 mmole L(-1) h(-1)), starting in the early exponential phase, induced CAT but did not increase SOD significantly. Gassing an early exponential-phase culture with O2 enriched (25 vol%) air resulted in increased activities of both SOD and CAT relative to control processes gassed continuously with air, while gassing the culture with 25 vol% O2 enriched air throughout the experiment, although inducing a higher base level of enzyme activities, did not increase the maximum SOD activity obtained relative to control processes gassed continuously with air. The profile of the specific activity of SOD (U mg CDW(-1)) appeared to correlate with dissolved oxygen levels in processes where no H2O2 addition occurred. These findings indicate that it is unsound to use the term "oxidative stress" to encompass a stress response produced by addition of a chemical (H2O2) or by elevated dissolved oxygen levels because the response to each might be quite different.
对经过基因工程改造以产生标记蛋白鸡蛋清溶菌酶的黑曲霉重组菌株（B1-D），在生物反应器系统的深层培养中，就其对“氧化应激”的敏感性进行了研究。通过添加外源过氧化氢或高溶解氧张力产生氧化应激，根据两种关键防御酶过氧化氢酶（CAT）和超氧化物歧化酶（SOD）的活性，对培养物的反应进行了检测。通常发现生物反应器中的分批培养物在稳定期/早期衰退期具有最高的CAT和SOD比活性（Umg×蛋白（-1））。从指数生长期早期开始连续添加H2O2（16 mmol L（-1）h（-1））可诱导CAT，但不会显著增加SOD。用富氧（25 vol%）空气对指数生长期早期的培养物进行通气，相对于用空气连续通气的对照过程，SOD和CAT的活性均增加，而在整个实验过程中用25 vol%富氧空气对培养物进行通气，尽管诱导了更高的酶活性基础水平，但相对于用空气连续通气的对照过程，并未增加获得的最大SOD活性。在未添加H2O2的过程中，SOD比活性（U mg CDW（-1））的曲线似乎与溶解氧水平相关。这些发现表明，使用“氧化应激”一词来涵盖由添加化学物质（H2O2）或升高溶解氧水平产生的应激反应是不合理的，因为对每种情况的反应可能有很大不同。
