Stress-resistant but phage-sensitive host mutants induced by phage T4 ghost adsorption

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Lytic phages primarily cause host cell lysis.
• The genetic impact of short-term phage-host interactions without gene transfer is largely unknown.

Purpose of the Study:

• To investigate the non-genetic transfer effects of lytic phage adsorption on host cell properties.
• To determine if phage adsorption can induce genetic alterations in surviving host cells.

Main Methods:

• Adsorption of lytic phage T4 to Escherichia coli.
• Measurement of spontaneous mutant frequency (antibiotic resistance).
• Analysis of gene expression, focusing on DNA polymerase IV (dinB), and specific gene mutations (tfaR, marR).

Main Results:

• Phage T4 adsorption increased E. coli spontaneous mutation frequency by 85-fold.
• Phage ghosts induced mutator strains via DNA polymerase IV upregulation, dependent on dinB.
• Surviving cells showed altered gene expression, increased resistance to oxidative and acid stress, but decreased resistance to phage T4.

Conclusions:

• Phage adsorption, even without lysis or gene transfer, rapidly induces genetic and physiological changes in surviving hosts.
• Induced mutator phenotypes may enhance host survival under stress, potentially benefiting phage propagation.
• Phage ghosts can act as agents of host adaptation and evolution.