Summary
In the present experiment, natural protozoan fauna and other microbial components in water extracts from shortgrass prairie soil were separated on the basis of size by differential filtration (8-, 5-, and 3-μm porosities). All extracts contained bacteria and fungi, along with a few very small flagellates (3-μm pore size filtrate); flagellates and a few small amoebae (5-μm pore size filtrate); and flagellates, small amoebae, and small ciliates (8-μm pore size filtrate). All microorganisms, except a few species of flagellates, were present in the centrifuge treatment. Each filtrate was added to sterile soil, and the population of each microbial group was determined after inoculation at intervals up to 80 days (at room temperature). Populations of all added groups decreased on initial addition to soil but then increased during the incubation. By following nitrogen, phosphorus, and CO2 dynamics, we observed impacts of protozoan grazing on bacteria, including mineralization of N from microbial biomass.
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Frey, J.S., McClellan, J.F., Ingham, E.R. et al. Filter-out-grazers (FOG): A filtration experiment for separating protozoan grazers in soil. Biol Fert Soils 1, 73–79 (1985). https://doi.org/10.1007/BF00255133
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DOI: https://doi.org/10.1007/BF00255133