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) 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 to 3 fold in E. coli relative to single-predator treatments. Transmission electron microscopy confirmed coinfection, 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.