title: Loss of colicinogeny in Escherichia coli strains infected by certain resistance factors.
abstract: The original observation that in wild-type colicinogenic Escherichia coli strains the introduction of some R factors abolish their colicin production was studied in certain col(+) strains bearing well-defined col factors. Two resistance (R) factors were used and introduced by conjugation in these strains, namely the 222 factor of Watanabe and a Salmonella typhimurium ST factor (coding for resistance to streptomycin and tetracycline only). The introduction of above mentioned R factors abolished the colicin production of col(+) strains most probably by elimination of col factors. All col factors, however, were not equally susceptible to elimination by the R factors tested, since colicin production in ML strains was abolished by infection by the 222 factor but not by the R factor of S. typhimurium ST, which is able to eliminate other col factors.
mesh_terms: D002701:Chloramphenicol / Q000494:pharmacology; D003087:Colicins / Q000096:biosynthesis*; D003090:Coliphages; D003227:Conjugation, Genetic; D003433:Crosses, Genetic; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation; D009268:Nalidixic Acid / Q000494:pharmacology; D013307:Streptomycin / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D003087:Colicins; D013449:Sulfonamides; D009268:Nalidixic Acid; D002701:Chloramphenicol; D013752:Tetracycline; D013307:Streptomycin