Sunlight Inactivation of Human Polymerase Chain Reaction Markers and Cultured Fecal Indicators in River and Saline Waters

• Published in: Water environment research 2013-08, Vol.85 (8), p.743-750
• Main Authors: Gilpin, Brent J., Devane, Megan, Robson, Beth, Nourozi, Fariba, Scholes, Paula, Lin, Susan, Wood, David R., Sinton, Lester W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bacteroidales; Bacteroidetes - genetics; Bacteroidetes - radiation effects; Bifidobacterium - genetics; Bifidobacterium - radiation effects; Bifidobacterium adolescentis; Continental surface waters; DNA damage; Drinking water and swimming-pool water. Desalination; E coli; Escherichia coli; Escherichia coli - genetics; Escherichia coli - radiation effects; Exact sciences and technology; Feces - microbiology; Fresh water; Freshwater; General purification processes; Genetic Markers; Humans; Natural water pollution; PCR markers; Pollution; Polymerase Chain Reaction; Product category rules; River water; Rivers - microbiology; Sea water; Seawater; Seawater - microbiology; Seawaters, estuaries; Signals; Sun; Sunlight; sunlight inactivation; Wastewaters; Water Microbiology; Water temperature; Water treatment and pollution
• ISSN: 1061-4303; 1554-7531
• DOI: 10.2175/106143012X13560205144290

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.