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Interaction of mutations affecting growth rate and resistance to streptomycin in pneumococci and streptococci
Abstract:
Krauss, Marjorie R. (New York University Medical Center, New York, N.Y.), James C. King, and Rody P. Cox. Interaction of mutations affecting growth rate and resistance to streptomycin in pneumococci and streptococci. J. Bacteriol. 92:1337-1344. 1966.-A strain of Streptococcus (Viridans group) was shown by transformation reactions to be the carrier of two interacting mutations. One produced resistance to streptomycin and a slow rate of growth; the only effect of the second was an increase in growth rate when it was added by transformation to streptococcal strains that had already been transformed to bear the first. Similar modifying mutations were observed in strains of streptococci and pneumococci into which the first mutation had been introduced by transformation.
Insights
Two interacting mutations were identified in streptococci. One mutation conferred streptomycin resistance and slowed growth, while a second mutation enhanced growth rate in resistant strains.
Area of Science:
- Microbiology
- Genetics
Background:
- Streptococci and pneumococci are significant bacterial pathogens.
- Understanding genetic mutations is crucial for studying bacterial adaptation and virulence.
Purpose of the Study:
- To investigate the interaction between mutations affecting bacterial growth rate and antibiotic resistance.
- To identify and characterize genetic elements that modify these traits in Streptococcus species.
Main Methods:
- Bacterial transformation experiments were used to introduce specific mutations into Streptococcus strains.
- Growth rates and streptomycin resistance levels were assessed in transformed and control strains.
Main Results:
- A mutation conferring streptomycin resistance and a reduced growth rate was identified.
- A second, independently acting mutation was found to increase the growth rate of streptomycin-resistant streptococci.
- Similar modifying mutations were observed in both streptococci and pneumococci.
Conclusions:
- Interacting mutations can modulate bacterial phenotypes, such as growth rate and antibiotic resistance.
- The identified mutations provide insights into the genetic mechanisms governing bacterial adaptation to environmental pressures like antibiotic exposure.