原生动物对细菌的捕食作用是存在于自然界微生物之间的重要父系之一。某些试验证明,在自然生态系中,原生动物对细菌贪婪的捕食作用,明显地影响到细菌的数量,是限制细菌数量的关键因子;但是,原生动物不可能消灭细菌,它们之间永远保持着动态的平衡,因为当原生动物对细菌的捕食达到一定极限时,被捕食的细菌和增殖的细菌基本相等,细菌的数量则不再减少。例如,Ostrolenk.M等报导,将E.coli加入自然土 Protozoan prey on bacteria is one of the important patrilobies that exist among the microorganisms in nature. Some experiments show that in natural ecosystems, the predatory effect of protozoans on bacteria predominantly affects the number of bacteria and is a key factor in limiting the number of bacteria; however, protozoa can not destroy bacteria and remain forever between them Dynamic equilibrium, because when protozoa reaches a certain limit on bacterial prey, prey bacteria and proliferating bacteria are basically the same, the number of bacteria is no longer reduced. For example, Ostrolenk.M et al. Report that E. coli is added to natural soil