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首页> 外文期刊>Applied Microbiology >Staphylococcal Enterotoxin B and Nuclease Production Under Controlled Dissolved Oxygen Conditions
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Staphylococcal Enterotoxin B and Nuclease Production Under Controlled Dissolved Oxygen Conditions

机译：受控溶解氧条件下葡萄球菌肠毒素B和核酸酶的产生

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Enterotoxin B, nuclease, and total exoprotein production by Staphylococcus aureus strain S-6 was studied in a 0.5-liter fermentor system. While these extracellular products were elaborated over a wide range of aeration rates, maximal production occurred within the very narrow range of 125 to 150 cm3 of air per min. The levels attained at the optimal aeration rate were not increased by maintaining a constant pH, although yield of enterotoxin:cell mass was highest at a constant pH of 7.0. During the growth cycle of the cultures, when aeration rate alone or aeration rate and pH were held constant, the dissolved oxygen (DO) levels, initially set at 100% of saturation, decreased to 5 to 10% 4 to 5 h after inoculation. The oxygen demand of the culture then maintained this level for an additional 4 to 6 h. This interval of low DO was characterized by maximal growth and exoprotein production. When the DO was controlled at a constant value throughout growth (by increasing or decreasing the airflow rate as appropriate), the culture demonstrated different optima for maximal growth and exoprotein production. A constant DO of 100% stimulated growth to extremely high densities, but the accumulation of toxin and nuclease was not observed. On the other hand, maintaining constant DO levels at 50 or 10% raised exoprotein levels higher than those achieved in a culture grown at the optimal aeration rate. Compared to the optimal aeration rate culture, the 10% DO culture yielded 20% more nuclease, 25% more toxin, and 40 to 50% more total exoprotein. These results indicate that it is the DO and not the aeration rate, per se, that is influential in controlling growth, toxin, nuclease, and total exoprotein production.
机译：在0.5升发酵罐系统中研究了金黄色葡萄球菌S-6菌株的肠毒素B，核酸酶和总外蛋白的产生。尽管这些细胞外产物在很宽的曝气速率下进行了精心设计，但最大产量却在每分钟125至150 cm3的非常狭窄的范围内发生。维持恒定的pH值并不会提高最佳曝气速率下的水平，尽管在7.0的恒定pH值下肠毒素：细胞团的产量最高。在培养物的生长周期中，当单独的通气速率或通气速率和pH保持恒定时，最初设置为饱和度100％的溶解氧（DO）水平在4至5小时后降至5％至10％接种。然后，培养物的需氧量再维持此水平4至6小时。低溶解氧的这个间隔的特征在于最大的生长和外蛋白的产生。当溶解氧在整个生长过程中都控制在一个恒定值时（通过适当增加或降低气流速率），培养物显示出最大生长量和外蛋白产量的不同最佳值。恒定的100％DO刺激生长至极高的密度，但未观察到毒素和核酸酶的积累。另一方面，将DO保持恒定在50％或10％时，其胞外蛋白水平要高于以最佳通气速率生长的培养物中达到的水平。与最佳通气率培养相比，DO培养10％产生的核酸酶增加20％，毒素增加25％，总外蛋白增加40％至50％。这些结果表明，控制溶解度，毒素，核酸酶和总外蛋白产量的因素是溶解氧而不是通气率本身。

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