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Differential Decay of Human Faecal Bacteroides in Marine and Freshwater
Citation:
Green, H. C., O. C. SHANKS, M. SIVAGANESAN, R. A. HAUGLAND, AND K. G. Field. Differential Decay of Human Faecal Bacteroides in Marine and Freshwater. Environmental Microbiology. Wiley-Blackwell Publishing, Hoboken, NJ, 13(12):3235-3249, (2011).
Impact/Purpose:
To inform the public.
Description:
Gene sequences from Bacteroides and relatives are being considered for the enumeration of aquatic fecal contamination and estimation of public health risk. To interpret these data, it is necessary to understand the decay of molecular and cultivated indicators and pathogens in environmental matrices. We measured concentration of fecal indicators and proposed contaminant markers (Enterol, HumM2, and Bacteroides targeted assays) in microcosms constructed by seeding sewage influent into marine and fresh water matrices that were exposed to either sunlight or dark treatments. We used Bayesian statistics with a delayed Chick-Watson model to estimate kinetic parameters for the decay of each target. DNA- and RNA-based targets decayed at roughly the same rate. Molecular markers survived longer in marine water. Sunlight increased the decay of cultured indicators and limited the survival of DNA and RNA markers, but had little effect on decay rates. Within each treatment all Bacteroides markers had similar decay profiles. Results demonstrate that water matrix is an important factor complicating quantitative source tracking and microbial risk assessment applications, and suggest that the role of extra-cellular DNA in signal persistence may be unimportant. This study also casts light on the interaction between cell type and environmental features on allochthonous (invasive) bacterial decay in fresh and marine environments.
