Fig. 4
From: A programmable CRISPR/Cas9-based phage defense system for Escherichia coli BL21(DE3)
a Sensitivity of BL21 cells without the type II-A CRISPR-Cas system and of strains containing a type II-A CRISPR-Cas system to phage infection: BL21(pT7-cas9, pT7-gRNA, prfp) infected with 1 μ of phage stock, cultured at 30 °C in the presence of 0.05 mM IPTG. The protein levels of RFP correspond to the change of red fluorescence value; asterisks indicate significant differences compared with the BL21(pT7cas9, prfp) (*P < 0.05). b Sensitivity of BL21 cells without the type II-A CRISPR-Cas system and of strains containing a type II-A CRISPR-Cas system to phage infection: BL21(pT7-cas9, pT7-gRNA, prfp) infected with 1 μl of phage stock, cultured at 30 °C in the presence of 0.05 mM IPTG. The protein levels of RFP correspond to the changes of red fluorescence; asterisks indicate significant differences compared with the BL21 (pT7cas9, prfp) (*P < 0.05)