Survival ofEscherichia coli in great salt lake water

Abstract

Survival ofEscherichia coli was studied in water from the Great Salt Lake, a highly saline lake with an ionic composition much like sea water. Samples used were from the most concentrated north arm (343.1 g l⁻¹ solids) and the less concentrated south arm (about 113 g l⁻¹ solids). At temperatures from 20°C to 9°C the bacterial death rate (k) for the north arm was −0.17 log day⁻¹ and the south arm and 1:3 dilution −0.28 log day⁻¹. Above 9°C the rate of death increased approximately exponentially and at 19°C the rate of death increased approximately exponentially and at 19°C the death rate was −1.31 log day⁻¹ in the north arm and −0.98 log day⁻¹ in the lower salinity water. These rates fall within those reported for sea water and are much higher than fresh water. Possible causes of death are discussed with the most likely being the high concentrations of minor elements or osmotic stress. The survival characteristics ofE. coli in waters with a sea water-like composition should require the same health concern as sea water regardless of the actual concentration of salt. High salt water of other ionic composition may behave differently, however.