TABLE 3.

Summary of results

PCR inserta	Red source	Results of electroporation
		Fresh aliquots		Frozen aliquots
		No. of colonies obtainedb	% Correct insertionc	No. of colonies obtainedb	% Correct insertionc
λPR-nptII	DY378	550	82	430	86
λPR-nptII	DH5α/pKD46	350	88	315	90
rrnA1-nptII	DY378	146	92	172	84
rrnA1-nptII	DH5α/pKD46	140	88	133	90
λPR-lacZ	DY378	224	ND	196	ND
λPR-lacZ	DH5α/pKD46	230	91	220	88

^aλP_R-nptII encodes nptII flanked by pTrun-cat homologies containing complementation of the λP_R promoter. rrnA1-nptII encodes nptII flanked by pTrun-cat homologies containing complementation of the rrnA1 promoter. λP_R-lacZ encodes β-galactosidase flanked by pTrun-cat homologies containing complementation of the λP_R promoter.

^bOne-fifth of each electroporation reaction mixture was plated and counted. Results represent the number of chloramphenicol-resistant colonies obtained per reaction mixture. Standard deviations of multiple platings from the same sample were less than 10% in all cases.

^cAt least 50 obtained colonies electroporated with either λP_R-nptII or rrnA1-nptII were tested for kanamycin resistance as described in Materials and Methods. The percentage of kanamycin-resistant colonies was determined accordingly. DH5α/pKD46/pTrun-cat colonies electroporated with λP_R-lacZ were plated on LB agar containing chloramphenicol, X-Gal, and IPTG, and the percentage of blue colonies was determined from total colonies (Fig. 2). The percentage of DY378/pTrun-cat blue colonies was not determined (ND) due to endogenous lacZ background activity.