Distinct ecophysiological characteristics of two genetically similar vibriophages

Vibrio parahaemolyticus is a marine bacterium and a causative agent of gastroenteritis in humans. Phages targeting V. parahaemolyticus serve as natural antagonists to this pathogen, significantly controlling its population and, consequently, disease outbreaks. In this study, two myoviruses, vB_VpaM_R20L (R20L) and vB_VpaM_R19R (R19R), were isolated and characterized against V. parahaemolyticus ATCC 17802^T. Despite their genomic resemblance, phages R19R and R20L displayed notable differences in physiological characteristics, particularly in infection dynamics and thermal stability. Both phages had a latent period of approximately 10 min; however, R19R demonstrated significantly greater replication efficiency, with a burst size of 388 PFU/cell compared to 90 PFU/cell for R20L. Thermal stability assays showed that R20L maintained survival rates of 80%–100% at 5 ℃–45 ℃ for over three days, while R19R's viability declined to 50% within 12 h under the same conditions. Furthermore, molecular dynamics simulations identified the influence of temperature on the thermal stability of phages, primarily through impact on the structural proteins. These findings suggest that subtle genomic variations may drive differences in physiological characteristics, highlighting the complexity of vibriophage-host interactions and their selection in response to natural environmental pressures.