The effect of road salt on the eating of bacteria or bacterivory by the ciliate, Tetrahymena thermophila, was followed in non-nutrient Osterhout's solution with Escherichia coli expressing green fluorescent protein. Bacterivory was impaired at between 0.025 and 0.050% w/v but the ciliates appeared to have normal morphologies and motilities, whereas at above 0.1%, bacterivory was blocked and many ciliates died. By contrast, E. coli remained viable, suggesting salt could alter predator-prey relationships in microbial communities. In nutrient medium, salt was not toxic and the ciliates grew. After growth in salt, ciliates consumed bacteria in 0.2% salt, indicating the salt acclimation of bacterivory. Bacteria and ciliates were added to urban creek samples to compare their capacity to support exogenous bacterivory. Even though samples were collected weekly for a year and be expected to have fluctuating salt levels as a result of deicing, all creek samples supported a similar level of bacterivory.
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