title: Sunlight inactivation of human polymerase chain reaction markers and cultured fecal indicators in river and saline waters.
abstract: Decay rates for sunlight inactivation of polymerase chain reaction (PCR) markers for total Bacteroidales, human-specific Bacteroidales, Escherichia coli, and Bifidobacterium adolescentis relative to cultured E. coli were investigated. The experiment used 100-L chambers of fresh water and seawater (paired with dark controls) seeded with human sewage and exposed to natural sunlight over three summer days. Culturable E. coli levels in sunlight-exposed chambers decreased by at least 3 logs on day 1, and by day 3 a total reduction of 4.5 to 5.5 logs was achieved in fresh water and seawater, respectively. In contrast, PCR detection of the four gene targets in sunlight-exposed chambers reduced by no more than 2 logs over the duration of the study (k(t) < 0.071 log(e) units h(-1)). Under these experimental conditions, PCR markers are considerably more conservative than culturable E. coli and can persist for extended periods of time following inactivation of E. coli.
authors.affiliation: Institute of Environmental Science and Research, P.O. Box, 29-181, Christchurch, New Zealand. Brent.Gilpin@esr.cri.nz
authors.forename: Brent J
authors.initials: BJ
authors.lastname: Gilpin
authors.forename: Megan
authors.initials: M
authors.lastname: Devane
authors.forename: Beth
authors.initials: B
authors.lastname: Robson
authors.forename: Fariba
authors.initials: F
authors.lastname: Nourozi
authors.forename: Paula
authors.initials: P
authors.lastname: Scholes
authors.forename: Susan
authors.initials: S
authors.lastname: Lin
authors.forename: David R
authors.initials: DR
authors.lastname: Wood
authors.forename: Lester W
authors.initials: LW
authors.lastname: Sinton
mesh_terms: D041963:Bacteroidetes / Q000235:genetics / Q000528:radiation effects*; D001644:Bifidobacterium / Q000235:genetics / Q000528:radiation effects*; D004926:Escherichia coli / Q000235:genetics / Q000528:radiation effects*; D005243:Feces / Q000382:microbiology; D005819:Genetic Markers; D006801:Humans; D016133:Polymerase Chain Reaction; D045483:Rivers / Q000382:microbiology; D012623:Seawater / Q000382:microbiology; D013472:Sunlight; D014871:Water Microbiology
chemical_list: D005819:Genetic Markers