Evaluation of a filtration/dispersion method for enumeration of particle-associated Escherichia coli.
The transport processes of microorganisms in storm-generated flows have not been clearly elucidated, limiting the ability of computational models to effectively design and evaluate watershed remediation plans. Although several studies have identified association with particulates as a critical factor in predicting microbial transport and fate, no generally accepted method exists for the identification of the planktonic and particle-associated fractions of microorganisms in water samples. In this study, a filtration/dispersion method proposed for quantification of these fractions was verified using laboratory-composed samples of bovine Escherichia coli and sterile topsoil. A statistical experimental design allowed quantification of potential sources of experimental error (e.g., filter retention, die-off), although no significant sources of methodological error were identified. On average, 78% of E. coli cells were particle associated after 1 h of contact time. Further application of the method was illustrated by an isotherm experiment examining the association of a bovine strain of E. coli with sterile topsoil. Further examination of this method in laboratory or field-based studies of microbial partitioning between the planktonic and particulate phases in surface runoff appears justified.
Krometis
Leigh-Anne H
LA
Dep. of Environmental Sciences, Gillings School of Global Public Health, Univ. of North Carolina, Chapel Hill, NC 27599-7431, USA. krometis@email.unc.edu
Dillaha
Theo A
TA
Love
Nancy G
NG
Mostaghimi
Saied
S