Compatibility behaviour of some newly isolated F-like R factor

The incompatibility reactions of four new R factors have been determined against reference plasmids of the compatibility groups FI, FII, FIII, FIV, FV, FVI and various not F-like groups. Two R factors have been found to belong to group FII, while one of the two other plasmids was incompatible with representatives of the FII and FI groups. The last R factor was incompatible with plasmids of FII and P groups. It seems, therefore, that R factors with incompatibility for more than one group of plasmids occur frequently in nature.