Quantitative Dual Predation by a Wild-type Bdellovibrio-like Organism and Lytic Bacteriophage Reveals Host-Specific Synergy

Bacteriophages and wild-type Bdellovibrio-and-like organisms (BALOs) are key microbial predators that influence bacterial population turnover, yet their potential synergy during co-infection remains poorly characterized. Here, we quantified dual predation by a wildtype BALO isolate ( EMS ) and a lytic phage ( M7f ) against Aeromonas sobria and Escherichia coli using synchronized single-cycle infections. Colony-forming units (CFU), plaque-forming units (PFU), and optical density (OD ₆₀₀ ) were monitored over time, supported by Bliss independence modeling and Kaplan–Meier survival analysis. Dual predation did not accelerate lysis onset but increased the magnitude of prey clearance by approximately 2–3-fold in E. coli relative to single-predator treatments. Transmission electron microscopy confirmed co-infection, revealing phage particles adsorbed to prey cells containing BALO-induced bdelloplasts. Together, these findings show that wild-type predators’ complementary infection modes, rapid phage lysis and slower BALO periplasmic invasion, create host-specific synergy. This quantitative framework offers mechanistic insights into natural co-predation and underscores the potential of integrated predator systems for microbial control.