Interaction of Escherichia coli with groundwater and reclaimed water biofilms

摘要

A laboratory reactor was developed to investigate the interaction of E. coli with multi-speeies biofilms and the effect of the biofilm on E. coli survival. Biofilms were developed on glass covcrslips under continuous flow of peptone-amended groundwater. Reactor flasks containing the glass coverslips were inoculated with a green fluorescent protein-labelled E. coli for a period of 6 days and then switched to flow-through of either groundwater or reclaimed water (treated sewage effluent) for a further 21 days. Reactor flasks which were treated in the same way but did not contain coverslips were used as controls. Attachment and survival of E. coli was monitored using fluorescence microscopy and enumeration of fluorescent colony-forming-units. E. coli was found to attach to the biofilms in all flasks but was able to persist for longer in the presence of groundwater compared to reclaimed water. In the groundwater flasks there was evidence for the detachment of some viable cells from the biofilm into the water-phase. Conversely, interaction with the biofilm was found to expedite the removal of E. coli in the flasks that contained reclaimed water.