Coli-aerogenes Differentiation in Water Analysis

Abstract

The various biochemical tests were critically studied in an effort to determine those best suited for differentiation of Bacterium coli and Bact. aerogenes The methyl-red and the Voges-Proskauer tests were least reliable. The indol and Koser''s citrate tests were most reliable, and serve as indicators of contaminants. Use of these 4 tests together is superior to any 3, and should be adopted for accurate differentiation of the coli-aerogenes group. Their application to 2093 cultures isolated from lake and well water gave 35.2% Bact. coli and 18.5% Bact. aerogenes, with the balance represented as mix tures, irregulars, and intermediates. Differentiation of cultures from water obtained after preliminary enrich ment in lactose broth is usually unsatisfactory and must be supplemented by some method of purification. 4 methods for purification of cultures having atypical re actions are presented.