Premium
Genetic Structure of an R Factor Conferring Ampicillin Resistance
Author(s) -
Hashimoto Hajime,
Tanaka Tokumitsu,
Mitsuhashi Susumu
Publication year - 1973
Publication title -
japanese journal of microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0021-5139
DOI - 10.1111/j.1348-0421.1973.tb00783.x
Subject(s) - tetracycline , ampicillin , gene , genetics , chloramphenicol , biology , escherichia coli , amp resistance , genetic recombination , recombination , microbiology and biotechnology , antibiotics
An R factor carrying resistant genes, ampicillin ( amp ), tetracycline ( tet ), chloramphenicol ( cml ), dihydrostreptomycin ( sir ), and sulfanilamide ( sul ), was analyzed by three genetic techniques: spontaneous segregation, transduction, and recombination. The R factor was stable in Shigella and Escherichia coli , but in Salmonella the ( cml.str.sul ) genes were spontaneously lost at a high frequency. Almost all of the transductants with Pl contained the five drug markers, but a very small number of them carried both tet and amp genes, or the ( amp.cml.str.sul ) genes. In conjugal transfer from a strain carrying a single type of R factor to R + recipient, the recombination took place between the amp and tet, amp and cml , and between the cml and str genes, at a frequency of 23.5, 39.5, and 3.0%, respectively. Crossover between the amp and transfer ( tra ) loci was not observed. A circular genetic model is proposed in which the genes are arranged in the order –tet9–tet1‐tra.amp–cml–str– .