EFFECT OF BACTERIAL SPECIFIC GROWTH RATE AND GROWTH IN BIOFILMS ON KINETICS OF INACTIVATION WITH MONOCHLORAMINE

摘要

Survival and growth of bacteria in drinking water distribution systems is commonly observed despite the maintenance of a disinfectant residual. The mechanisms governing survival are not fully understood, but it has been suggested that microorganisms respond to environmental stresses in a way that decreases susceptibility to disinfection. Sub-maximal growth rates and sub-optimal growth temperatures have been shown to increase Escherichia coli resistance to chlorine dioxide. Growth at low specific growth rates has been reported to reduce sensitivity of E. coli to thermal, UVA and solar disinfection. These studies suggest that lower growth rates induce phenotypes that are less susceptible to inactivation. Low specific growth rate, for example, induces the general stress response (rpoS) system in E. coli. The present study examines the effect of specific growth rate and growth in biofilms on the inactivation kinetics of E. coli, a model drinking water pathogen, in the presence of the disinfectant residual monochloramine.