title: Decay kinetics of microbial source tracking (MST) markers and human adenovirus under the effects of sunlight and salinity.
abstract: Artificial seawater and freshwater microcosms inoculated with raw sewage were set up to compare the persistence of microbial source tracking (MST) markers (i.e. Bacteroides thetaiotaomicron (B. theta), Methanobrevibacter smithii (M. smithii), human polyomaviruses JC and BK (HPyVs)) and human adenoviruses under different sunlight intensity and salinity. PMA pretreatment successfully eliminated the false-positive detection of dead bacterial cells in the model-development experiment. The results were then validated using real environmental matrices in microcosms inoculated with raw sewage. The genome concentrations of the targets followed a first-order decay pattern with 90% reduction of the initial amounts in <5days for both artificial and natural surface waters. Decay rate constant (k1) were developed microorganisms in artificial water matrices. Due to the different water environment conditions, improved decay rates (k2) incorporated with sunlight, TSS and TOC adjustment coefficients were used for validation of the natural water matrices. Based on the predictive squared correlation coefficient (Q2F) and root-mean-square error (RMSE) validation criteria, the improved k2were able to provide better prediction on the survival of target microorganisms in environmental surface waters (Q2F>0.6 and RMSE ranged from 0.05 to 1.81). For microbial source tracking purposes, HPyVs are suggested to be better MST markers in freshwater, while B. theta is recommended for seawater based on the decay models developed in this study. The targeted DNA of M. smithii should only be used to indicate recent human faecal pollution in surface waters due to their faster decay than human adenoviruses.
authors.affiliation: Department of Civil & Environmental Engineering, The National University of Singapore, Block, E1A, #07-03,1 Engineering Drive 2, 117576, Singapore.
authors.forename: Liang
authors.initials: L
authors.lastname: L
authors.affiliation: Department of Civil & Environmental Engineering, The National University of Singapore, Block, E1A, #07-03,1 Engineering Drive 2, 117576, Singapore.
authors.forename: Goh
authors.initials: G
authors.lastname: S G
authors.affiliation: Department of Civil & Environmental Engineering, The National University of Singapore, Block, E1A, #07-03,1 Engineering Drive 2, 117576, Singapore; NERI - NUS Environmental Research Institute, 2nd floor, T-Lab Building, 5A Engineering Drive 1, 117411, Singapore. Electronic address: ceeginyh@nus.edu.sg.
authors.forename: Gin
authors.initials: G
authors.lastname: K Y H
mesh_terms: D000260:Adenoviruses, Human / Q000302:isolation & purification* / Q000528:radiation effects; D004784:Environmental Monitoring; D005243:Feces; D006801:Humans; D007700:Kinetics; D008962:Models, Theoretical; D016133:Polymerase Chain Reaction; D054712:Salinity; D013472:Sunlight; D014871:Water Microbiology
keywords: Enteric viruses; External validation criterion; Microbial source tracking (MST) markers; Multiple linear regression; Salinity; Sunlight