title: Simple medium that preserves low concentrations of Escherichia coli for use in the water bacteriology proficiency test.
abstract: A medium containing (per liter) 6.8 g of sodium acetate trihydrate, 3.4 g of potassium dihydrogen phosphate, and 0.1 g of magnesium sulfate heptahydrate (medium pH, 5.85 plus/minus 0.05) was developed for use in a water bacteriology proficiency test. The medium maintained 80 to 100 % viability of inoculated Escherichia coli at temperatures up to 31 degrees C for at least 12 days, while the concentrations of bacteria in the medium were as low as 20 bacteria per 100 ml. The medium remained stable after a year of storage. It has been used successfully to preserve bacteria in nine statewide bacteriology proficiency tests for potable and nonpotable water and has also been used in a nationwide pilot test. This report presents the results of these tests.
authors.affiliation: New York State Department of Health, Albany 12201-0509.
authors.forename: M
authors.initials: M
authors.lastname: Chen
mesh_terms: D003470:Culture Media; D004926:Escherichia coli / Q000254:growth & development*; D013696:Temperature; D014871:Water Microbiology; D014881:Water Supply / Q000592:standards*
chemical_list: D003470:Culture Media