After the plasma ion bombardment, the samples were recovered
in 20 μl of de-ionized water and divided into six parts for gene transformation
(3 μl used for transformation each time). The plasmid
pUC19 was transformed into E. coli (DH5α) competent cells using
the standard electroporation. The lacZ gene fragment was first ligated
into plasmid DNA pUC19 (digested by NdeI/HindIII) and then the
DNA was transformed into E. coli (DH5α) competent cells. In the
transformation process, the sample was first mixed with pure
water, and then the DNA solution was put into 100 μl of Lysogeny
broth (LB) medium with a high concentration of the bacterial cells,
followed by electroporation at 1.8 kV.