Bacterivores

A bacterivore is an organism whose diet consists primarily of bacteria. Bacterivory occurs across a broad range of taxa, from single-celled protists such as ciliates and heterotrophic flagellates to small metazoans including nematodes and microarthropods, as well as some microinvertebrates that inhabit soils and sediments. Through grazing on bacterial populations, bacterivores regulate bacterial abundance and community composition and contribute to nutrient and carbon cycling in ecosystems.

In aquatic ecosystems, bacterivores are central components of the microbial loop. Heterotrophic flagellates and ciliates consume bacterioplankton, converting bacterial biomass into predator biomass and carbon dioxide, while releasing dissolved organic matter that can fuel other microorganisms. The activity of bacterivores helps transfer energy to higher trophic levels, as bacterivores are consumed by larger protists and microinvertebrates.

In soils and sediments, bacterivores such as bacterivorous nematodes, protozoa, and microarthropods feed on bacteria and other microbes, contributing to mineralization and nutrient release. Their feeding influences soil structure, microbial community dynamics, and the fate of organic matter, and they interact with other components of the soil food web, including fungi and detritivores.

Measuring bacterivory often uses methods such as fluorescently labeled bacteria uptake assays, stable isotope tracing, and ingestion-rate experiments. Advances in imaging and molecular techniques help identify which taxa are grazing on bacteria and quantify grazing pressure in different environments.