摘要
Enterohemorrhagic Escherichia coli strains (EHEC) have caused many foodborne outbreaks. Bacterivorous protozoa could remove bacteria from aquatic systems. We analyzed the ciliate protozoan population changes influenced by EHEC co-culture in activated sludge. EHEC and non-EHEC control E. coli cells were added to activated sludge samples in microcosms. The ciliate population changes were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis. EHEC and non-EHEC fed ciliate protozoan populations were different from each other and the no bacteria added controls based on the additive main effects and multiplicative interaction model (AMMI) analysis. Ciliate species were identified by 18S rDNA clone libraries. The 18S rDNA clones from the original sludge sample were identified as Epistylis wenrichi (70%) and Prorodon teres (30%), while clones from EHEC treated sludge sample were identified as P. teres (52%), Vorticella fusca (41%), Dexitrichides pangi (5%), and Opisthonecta henneguyi (2%). This study could provide helpful information about ciliate protozoan population changes caused by different E. coli strains in wastewater treatment plants, which could be useful for preventing and tracking E. coli outbreaks.
Enterohemorrhagic Escherichia coli strains (EHEC) have caused many foodborne outbreaks. Bacterivorous protozoa could remove bacteria from aquatic systems. We analyzed the ciliate protozoan population changes influenced by EHEC co-culture in activated sludge. EHEC and non-EHEC control E. coli cells were added to activated sludge samples in microcosms. The ciliate population changes were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis. EHEC and non-EHEC fed ciliate protozoan populations were different from each other and the no bacteria added controls based on the additive main effects and multiplicative interaction model (AMMI) analysis. Ciliate species were identified by 18S rDNA clone libraries. The 18S rDNA clones from the original sludge sample were identified as Epistylis wenrichi (70%) and Prorodon teres (30%), while clones from EHEC treated sludge sample were identified as P. teres (52%), Vorticella fusca (41%), Dexitrichides pangi (5%), and Opisthonecta henneguyi (2%). This study could provide helpful information about ciliate protozoan population changes caused by different E. coli strains in wastewater treatment plants, which could be useful for preventing and tracking E. coli outbreaks.
