Droffner M L, Yamamoto N
Woods End Research Laboratory, Mt. Vernon, Maine 04352.
Appl Environ Microbiol. 1992 May;58(5):1784-5. doi: 10.1128/aem.58.5.1784-1785.1992.
When Escherichia coli was incubated at the growth-refractory temperatures of 48 and 54 degrees C, expression of the cel operon was demonstrated by phospho-beta-glucosidase activity. This enzyme activity was also detected at the growth-refractory temperatures in Salmonella typhimurium and Pseudomonas aeruginosa. Thermotolerant and mesothermophilic mutants of E. coli, S. typhimurium, and P. aeruginosa, able to grow with generation times of 30 to 40 min at 48 and 54 degrees C, exhibited phospho-beta-glucosidase activity at their growth temperatures of 48 and 54 degrees C. Thus, the cel operon previously described as a cryptic operon in E. coli and S. typhimurium was found to be expressed at growth-refractory temperatures of the mesophilic parent and growth-permissive temperatures (48 and 54 degrees C) of the thermotolerant and mesothermophilic mutants.
当大肠杆菌在48℃和54℃这两个不利于生长的温度下培养时，通过磷酸-β-葡萄糖苷酶活性证明了cel操纵子的表达。在鼠伤寒沙门氏菌和铜绿假单胞菌中，在不利于生长的温度下也检测到了这种酶活性。大肠杆菌、鼠伤寒沙门氏菌和铜绿假单胞菌的耐热和嗜温突变体能够在48℃和54℃下以30至40分钟的代时生长，在其48℃和54℃的生长温度下表现出磷酸-β-葡萄糖苷酶活性。因此，先前在大肠杆菌和鼠伤寒沙门氏菌中被描述为隐蔽操纵子的cel操纵子，发现在嗜温亲本的不利于生长的温度以及耐热和嗜温突变体的允许生长温度（48℃和54℃）下都有表达。
