Optimum Temperature for Differentiation of Escherichia coli from Other Coliform Bacteria

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Abstract
Temps. of 42[degree], 44[degree] and 46[degree]C were used to determine the most selective temp. for E. coli over other caliform bacteria in the authors'' medium consisting of 1% peptone, 0.5% NaCl, 0.15% potassium dihydrogen phosphate, 0.4% di-potassium hydrogen phosphate and 0.3% of carbohydrate (dextrose, lactose or mannitol). An incubator temp. of 45.5[degree]-46[degree]C (temp. of medium in tube 45.2-45.7[degree]C) was found most selective. Most strains of Aerobacter cloacae and Citrobacter were inhibited at 44[degree]C when lactose was used but a large percentage of the A. aerogenes strains produced gas. A temp. of 42[degree]C was much less inhibitory. MacConkey''s lactose bile medium was less selective than the authors'' medium especially when incubation was in a water bath.