Transformation efficiency of tested strains using LB culture medium.

aAt the time of plating, the 168 and 168-pLK culture contained 1.3*109 viable cells/ml, the NCIB3610-pLK culture contained 0.9*109 viable cells/ml, and the JW49 contained 1.0*109 viable cells/ml. For transformations 6 µg chromosomal DNA from strain JWV184 per ml culture was used. - = not tested.