title: Bacterial regrowth in water reclamation and distribution systems revealed by viable bacterial detection assays.
abstract: Microbial regrowth needs to be managed during water reclamation and distribution. The aim of present study was to investigate the removal and regrowth of Escherichia coli (E. coli) and Salmonella in water reclamation and distribution system by using membrane integrity assay (PMA-qPCR), reverse transcriptional activity assay (Q-RT-PCR) and culture-based assay, and also to evaluate the relationships among bacterial regrowth, and environmental factors in the distribution system. The results showed that most of the water reclamation processes potentially induced bacteria into VBNC state. The culturable E. coli and Salmonella regrew 1.8 and 0.7 log10 in distribution system, which included reactivation of bacteria in the viable but non-culturable (VBNC) state and reproduction of culturable bacteria. The regrowth of culturable E. coli and Salmonella in the distribution system mainly depended on the residual chlorine levels, with correlations (R(2)) of -0.598 and -0.660. The abundances of membrane integrity and reverse transcriptional activity bacteria in reclamation effluents had significant correlations with the culturable bacteria at the end point of the distribution system, demonstrating that PMA-qPCR and Q-RT-PCR are sensitive and accurate tools to determine and predict bacterial regrowth in water distribution systems. This study has improved our understanding of microbial removal and regrowth in reclaimed water treatment and distribution systems. And the results also recommended that more processes should be equipped to remove viable bacteria in water reclamation plants for the sake of inhibition microbial regrowth during water distribution and usages.
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Yi-wen
authors.initials: YW
authors.lastname: Lin
authors.affiliation: Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China. Electronic address: lidanfudan@fudan.edu.cn.
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA.
authors.forename: April Z
authors.initials: AZ
authors.lastname: Gu
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Si-yu
authors.initials: SY
authors.lastname: Zeng
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: hemiao@tsinghua.edu.cn.
authors.forename: Miao
authors.initials: M
authors.lastname: He
mesh_terms: D001681:Biological Assay; D002713:Chlorine / Q000494:pharmacology; D004269:DNA, Bacterial / Q000032:analysis; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012475:Salmonella / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D014871:Water Microbiology; D014873:Water Pollutants / Q000032:analysis; D018508:Water Purification
chemical_list: D004269:DNA, Bacterial; D014873:Water Pollutants; D002713:Chlorine
keywords: PMA-qPCR assay; Q-RT-PCR assay; Regrowth; Viable but non-culturable (VBNC) bacteria; Water reclamation and distribution system