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Alteration of Host Specificity to Lytic Bacteriophages in Streptococcus cremoris

R P Sinha1

  • 1Food Research Institute, Research Branch, Canada Agriculture, Ottawa, Ontario, Canada K1A 0C6.

Applied and Environmental Microbiology
|August 1, 1980
PubMed

Insights

A mutant Streptococcus cremoris strain resistant to acriflavine exhibited altered phage resistance and sensitivity. Infection by bacteriophage sc607 caused abortive infection, suggesting a protein-mediated post-adsorption event.

Area of Science:

  • Microbiology
  • Bacteriology
  • Virology

Background:

  • Streptococcus cremoris is a key dairy starter culture.
  • Bacteriophages are viruses that infect bacteria and can cause significant losses in industrial fermentations.
  • Understanding phage-host interactions is crucial for preventing phage contamination.

Purpose of the Study:

  • To characterize a mutant Streptococcus cremoris strain with altered bacteriophage interactions.
  • To investigate the mechanism of bacteriophage resistance and abortive infection in the mutant strain.

Main Methods:

  • Isolation of an acriflavine-resistant mutant of Streptococcus cremoris ML1.
  • Testing the mutant strain's sensitivity and resistance to various virulent bacteriophages.
  • Analyzing the interaction of bacteriophage sc607 with the mutant strain, including adsorption, cell killing, and nucleic acid synthesis.

Main Results:

  • The mutant strain displayed a reversed phage resistance/sensitivity profile compared to the parental strain.
  • Infection by bacteriophage sc607 led to abortive infection (cell killing without progeny phage production).
  • Abortive infection was a post-adsorption event, dependent on protein synthesis and inhibited by chloramphenicol, with a rapid cessation of RNA synthesis.

Conclusions:

  • The acriflavine-resistant mutant exhibits significant alterations in bacteriophage host specificity.
  • Abortive infection by bacteriophage sc607 in the mutant strain suggests a novel defense mechanism.
  • The observed phenomena resemble prophage-mediated interference, indicating potential applications in phage resistance strategies.

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