Shedding light on microbial predator-prey population dynamics using a quantitative bioluminescence assay

Area of Science:

• Microbiology
• Bacteriology
• Predator-prey dynamics

Background:

• Bioluminescence in prey bacteria is a key indicator of their physiological state.
• Bdellovibrio bacteriovorus is a predatory bacterium that targets Gram-negative bacteria.
• Understanding bacterial predation dynamics is crucial for microbial ecology and biotechnology.

Purpose of the Study:

• To investigate the factors influencing bioluminescence loss in prey bacteria during Bdellovibrio bacteriovorus predation.
• To quantify the extent of premature prey lysis and its relationship with predator-to-prey ratio (PPR).
• To develop a predictive model for bacterial predator-prey populations.

Main Methods:

• Comparative predation assays using bioluminescent Escherichia coli strains with heat-labile and heat-stable luciferases.
• Analysis of bioluminescence loss in relation to varying predator-to-prey ratios (PPR).
• Fluorescence microscopy to detect and quantify premature prey lysis.
• Development of a modified Lotka-Volterra model incorporating prey lysis.

Main Results:

• Bioluminescence loss was independent of prey luciferase stability.
• Prey bioluminescence loss was not directly proportional to PPR, with increased loss at higher ratios.
• Premature prey lysis was observed and increased significantly with higher PPRs (5% at PPR 10-20, 15% at PPR 90).
• Accurate estimation of predator numbers was achieved within 1 hour at PPR ≥ 6.

Conclusions:

• Bacterial protein stability does not explain bioluminescence quenching during Bdellovibrio bacteriovorus predation.
• Premature lysis of prey contributes significantly to the observed bioluminescence reduction.
• A modified Lotka-Volterra model accurately predicts prey and bdelloplast populations, accounting for lysis.