Bacteriophage T4 propagation in E.coli exposed to severe substrate limitation.

Abstract

Understanding bacteriophage propagation on bacteria in different physiological conditions is imperative for predicting phage therapy efficacy on various bacterial infections, especially chronic ones. We investigated phage T4 propagation on bacteria E.coli grown in a chemostat at very low dilution rates extending down to 0.027 h^-1 and bacteria exposed to nutrient deprivation. An increase in adsorption constant and latent period with dilution rate D decrease and burst size being proportional to dilution rate (D) was confirmed, consistent with previously published results, extending validity of previous findings. Additional bacterial exposure to starvation, either through nutrient cessation or transferring bacteria into SM buffer, sustained phage propagation during first hours of starvation and diminished to formation of a single phage per infected cell after 24 h. Nutrient deprivation effects were investigated on fast growing bacteria and bacteria in a death phase. While no phage generation was observed within bacteria in death phase, fast growing bacteria transferred into SM buffer generated a single phage within 48 h without lysis, indicating that bacterial exposure to nutrient depleted conditions triggers a so called "scavenger response" whose intensity depends on starvation exposure time.