Recoverability of <scp> Listeria monocytogenes </scp> after coculture with <scp> Tetrahymena pyriformis </scp>

Bactivory by protozoa is a major factor that limits the number of bacteria in nature and may control the presence of Listeria monocytogenes. The effectiveness of Tetrahymena pyriformis destruction of L. monocytogenes was measured. Within 1 hr, 35–40 T. pyriformis cells ingested an average of 1,219 CFU of L. monocytogenes. Gentamicin was then added to kill un‐ingested Listeria. In 24 hr, the recoverable bacteria were reduced at an exponential rate to undetectable levels (