Protists and nematodes are the key determinants of the soil microbiome. They feed on bacteria and fungi and thereby change their composition. So far, this role is little investigated with knowledge remaining merely on the fact that the microbiome predators reduce microbiome biomass and composition.
In two current studies we now show that the effect of predators on the microbiome also translates to functional changes. In the first we show that protists and nematodes have positive role a role on plant performance via interactions and stimulation of plant-beneficial arbuscular mycorrhizal fungi.
This study we just published in Microbiome.
But there is more: microbiome predation also seems to play a role in changing the activity of the microbiome. By adding bacteria and fungi to sterile litter in a controlled laboratory study we could show that the addition of the model protist Physarum polycephalum increases microbial decomposition by up to 50%! Meaning: predators are important catalysers of microbial processes. We just published this study in The ISME Journal (see linked blog here).
Both studies thus show that protists and nematodes are important microbiome engineers with their activity changing microbial functioning and likely important ecosystem services!