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首页> 外文期刊>Applied Microbiology >Effect of Glucose and Low Oxygen Tension on l-Asparaginase Production by a Strain of Escherichia coli B
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Effect of Glucose and Low Oxygen Tension on l-Asparaginase Production by a Strain of Escherichia coli B

机译：葡萄糖和低氧张力对大肠杆菌B菌株产生L-天冬酰胺酶的影响

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摘要

Cultural and nutritional requirements for maximum l-asparaginase synthesis were determined. Conventional aerobic and anaerobic fermentations were not satisfactory. The former yielded larger quantities of cells containing minimal amounts of l-asparaginase, whereas the latter supplied only minute amounts of bacteria that contained an abundance of enzyme. However, the combination of these classical methods, i.e., allowing growth to proceed aerobically until the mid to late exponential phase and then forcing the facultative microbial cells toward anaerobic metabolism by static incubation, produced 2.6 international units of enzyme per ml of fermentation broth when glucose was present. Enzyme synthesis was not induced by terminating aeration-agitation in the absence of glucose, nor was it induced in the presence of glucose when aeration was continued. Use of 0.2 m phosphate buffer resulted in a constant pH near the optimum value of 7.5 during l-asparaginase formation. Addition of 0.05% l-asparagine prior to induction was also beneficial, but other amino acids or their catabolites failed to increase biosynthesis of l-asparaginase.
机译：确定了最大的l-天冬酰胺酶合成的文化和营养要求。常规的需氧和厌氧发酵不能令人满意。前者产生的细胞中含有最少量的l-天冬酰胺酶，而后者产生的细菌数量却很少。然而，这些经典方法的组合，即允许有氧生长直至指数期的中后期，然后通过静态孵育迫使兼性微生物细胞进行厌氧代谢，当葡萄糖加入葡萄糖后，每毫升发酵液产生了2.6国际单位酶。存在。在不存在葡萄糖的情况下，通过终止曝气搅拌不会诱导酶的合成，在继续通气的情况下，在葡萄糖的存在下也不诱导酶的合成。在天冬酰胺酶形成过程中，使用0.2 m磷酸盐缓冲液会产生恒定的pH，接近7.5的最佳值。在诱导之前添加0.05％的l-天冬酰胺也是有益的，但是其他氨基酸或其分解代谢物不能增加l-天冬酰胺酶的生物合成。

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