title: Inactivation mechanism of chlorination in Escherichia coli internalized in Limnoithona sinensis and Daphnia magna.
abstract: Zooplankton may harbor microorganisms in the aquatic environment, thus protecting them from disinfection during drinking water treatment. However, few studies have evaluated the protective effect of internalization by zooplankton against bacterial disinfection. In this study, we investigated the role of zooplankton (Limnoithona sinensis and Daphnia magna) as a refuge for ingested bacteria against inactivation by chlorination. Only 30% of chlorine reached the internalized bacteria inside the digestive tract of zooplankton. However, this was sufficient to achieve 1.4 log inactivation of internalized Escherichia coli in L. sinensis and 1.2 log inactivation in D. magna at Ct values of 80 mg min/L. Inactivation of internalized bacteria was achieved through the active transfer of free chlorine in the bulk water into the zooplankton digestive tract during grazing activity. D. magna was more sensitive to hypochlorous acid than L. sinensis, and its grazing behavior was inhibited during the inactivation experiment.
authors.affiliation: Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China. Electronic address: hit_lintao@163.com.
authors.forename: Tao
authors.initials: T
authors.lastname: Lin
authors.affiliation: Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China. Electronic address: cw5826@hhu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: College of Environment, Hohai University, Nanjing 210098, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Cai
mesh_terms: D000818:Animals; D002713:Chlorine / Q000494:pharmacology*; D033342:Copepoda / Q000382:microbiology*; D003621:Daphnia / Q000382:microbiology*; D004203:Disinfection; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D041981:Gastrointestinal Tract / Q000382:microbiology; D054879:Halogenation; D050296:Microbial Viability; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods; D015048:Zooplankton / Q000382:microbiology
chemical_list: D002713:Chlorine
keywords: Disinfection; Escherichia coli; Inactivation; Internalized bacteria; Zooplankton