Behavior of lead in a model microbial predator-prey system

Area of Science:

• Environmental Microbiology
• Biogeochemistry
• Ecotoxicology

Background:

• Microbial predation significantly impacts the environmental fate of toxic trace metals.
• Metals can be released, retained, or transferred through predator-prey interactions.
• Aqueous metal ions can influence microbial predator growth and predation rates.

Purpose of the Study:

• To investigate the effects of lead (Pb) on microbial predator-prey dynamics.
• To elucidate the pathway and fate of Pb during predator-prey interactions.
• To develop a model describing predator-prey dynamics and Pb behavior.

Main Methods:

• Utilized a model system with the protozoan Tetrahymena thermophila (predator) and Pseudomonas putida (prey).
• Measured growth parameters in batch reactors with varying Pb concentrations.
• Employed established methods to track dissolved, prey-bound, predator-bound, and ingested Pb.
• Investigated the impact of prey density on predation and Pb phase distribution.

Main Results:

• Lead (Pb) altered kinetic parameters of prey consumption and growth in T. thermophila.
• Ingested Pb was associated with the predator through ingestion and adsorption.
• Pb was excreted bound to T. thermophila waste matter.
• Pb phase distribution was influenced by predator-prey interactions.

Conclusions:

• Microbial predation is a key process in the biogeochemical cycling of toxic metals like Pb.
• Pb affects microbial predator kinetics, influencing its own environmental fate.
• A preliminary model can describe predator-prey dynamics and Pb fractionation.