Dagert M, Ehrlich S D
Gene. 1979 May;6(1):23-8. doi: 10.1016/0378-1119(79)90082-9.
Escherichia coli cells are 4--6 times more transformable and 20--30 times more competent after 24 h incubation in cold calcium chloride than immediately after calcium chloride treatment. With 24-h-old competent cells we obtained routinely 2 . 10(7) transformants per microgram of pBR322 DNA, and transformed over 20% of viable cells.
在冷氯化钙中孵育24小时后,大肠杆菌细胞的转化率比氯化钙处理后立即提高4至6倍,感受态能力提高20至30倍。使用培养24小时的感受态细胞,我们通常每微克pBR322 DNA可获得2×10⁷个转化子,并使超过20%的活细胞发生转化。