Linkage of K99 production and STa activity in a plasmid of an Escherichia coli porcine isolate.

An Escherichia coli strain ZP118 of porcine origin was shown to harbor a 68-megadalton (Md) plasmid coding for a colonization factor K99 and heat-stable enterotoxin (STa), and a self-transmissible 51-Md plasmid coding for drug resistance. One of the transconjugants obtained by mating between ZP118 and E. coli C was found to harbor a 90-Md plasmid coding for K99, STa and drug resistance. Restriction endonuclease analysis suggested that the 90-Md plasmid could be a recombinant between the 68-Md plasmid and the 51-Md plasmid.