Experimental Listeria-Tetrahymena-Amoeba food chain functioning depends on bacterial virulence traits.

Background: Some pathogenic bacteria have been developing as a part of terrestrial and aquatic microbial ecosystems. Bacteria are consumed by bacteriovorous protists which are readily consumed by larger organisms. Being natural predators, protozoa are also an instrument for selection of virulence traits in bacteria.

Listeria monocytogenes virulence factor Listeriolysin O favors bacterial growth in co-culture with the ciliate Tetrahymena pyriformis, causes protozoan encystment and promotes bacterial survival inside cysts.

Background: The gram-positive pathogenic bacterium Listeria monocytogenes is widely spread in the nature. L. monocytogenes was reported to be isolated from soil, water, sewage and sludge.