Purified Cas9 (100 ng) or dCas9 (100 ng) was incubated with mecA DNA (100 ng) and sgRNA (100 ng) in reaction buffer containing 20 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES),100 mM NaCl, 5 mM MgCl2, and 0.1 mM ethylene diaminete traaceticacid (EDTA) (pH 6.5) for 1 h at 37 ℃.