bacterivorous

Bacterivorous describes organisms that obtain energy and carbon primarily by consuming bacteria. In practice, it refers to a trophic strategy used by many protists and some micrometazoans. Bacterivory is usually achieved by phagocytosis or grazing on bacterial biofilms and suspensions, with digestion inside food vacuoles.

In aquatic systems, bacterivory is a key link in the microbial loop, converting bacterial production into biomass that fuels higher trophic levels and releasing nutrients for microbial uptake. Predation on bacteria can regulate bacterial community composition and influence carbon and nutrient cycling. In soils and sediments, bacterivores contribute to nutrient mineralization and soil structure by releasing dissolved organic matter and inorganic nutrients, and by dispersing microbial cells.

Across ecosystems, common bacterivores include unicellular eukaryotes such as ciliates (e.g., Paramecium, Tetrahymena), flagellates, and amoebae, as well as micro-arthropods and nematodes that feed on bacteria. The efficiency of bacterivory depends on grazer size, bacterial prey size, access to biofilms, and environmental conditions. Bacterivorous organisms can employ various feeding modes, including selective grazing on specific bacterial taxa.

Researchers study bacterivory with methods like dilution assays, uptake of fluorescently labeled bacteria, and stable isotope tracers, though interpretations can be complex due to mixed diets and microbial turnover.