It's a common bacterium and most strains of E. Coli are not harmful to people, in fact, they provide us with some beneficial properties.

它是常见菌,且大多数种类的菌株对人类无害,实际上还给了我们颇多裨益

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It was found in strain R, a particular strain of E.coli, and it was the first one found, There's a nomenclature that's evolved for this.

酶被发现于R菌株,大肠杆菌中一种特别的菌株,又是被发现的第一种内切酶,有一种专门为此制定的命名法

耶鲁公开课 - 生物医学工程探索课程节选