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Selective enrichment of R− segregants as the main mechanism of ‘curing’ of the R factor by acridine dyes

Published online by Cambridge University Press:  14 April 2009

Masanosuke Yoshikawa
Masanosuke Yoshikawa
Affiliation:
Department of Bacterial Infection, The Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, Japan

Summary

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By the use of appropriate strains of Escherichia coli, Shigella flexneri and Salmonella typhimurium with and without an R factor, R100, the mechanism of ‘curing’ of R factor by acridine dyes was examined. This R factor was shown to confer increased sensitivity to acriflavine upon the host cells. E. coli strain W-3630, once infected with R100, has never been observed to segregate R− cells. When mixtures of R+ and R− cells of this strain were grown in acriflavine broth, the proportion of R− cells increased and was also correlated with the proportion in the initial inoculum. Other bacterial strains carrying R100 segregate R~ cells spontaneously. Growth tests starting with varying proportion of R+ and R− cells of these strains in acriflavine broth also gave a marked correlation between the initial and final proportions of R− cells, and indicated that the main cause of ‘curing’ the R factor was the selective enrichment of R− segregants present in the initial inocula or arising spontaneously during growth of the R+ culture. These results suggest that the mechanisms underlying the ‘curing’ of F and R factors are different. Tests with several acridine dyes gave results similar to those with acriflavine.

Type
Research Article
Information
Genetics Research , Volume 17 , Issue 1 , February 1971 , pp. 9 - 16
Copyright
Copyright © Cambridge University Press 1971

References

REFERENCES

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