The Utilisation of Citrates and the Fermentation of Cellobiose by Strains ofBacterium ColiIsolated from Human Faeces

Of 585 strains of lactose-fermenting aerobes each isolated from faeces of a different person, 501 did not utilise citrate or ferment cellobiose; 20 were citrate negative and cellobiose positive; 27 were cellobiose negative and citrate positive; and 37 were positive to both tests. 2. Almost 10 per cent, of the strains isolated were indol negative. 3. One culture was methyl-red negative and Voges-Proskauer positive. Two were positive to both tests. The rest were methyl-red positive and Voges-Proskauer negative. 4. It is concluded that the results are not favourable to the use of the citrate or the cellobiose test in routine water analysis. 5. A discussion of the taxonomy of the lactose-fermenting aerobes is given. Only two species, Bacterium coli (Escherich) L. and N., and Bacterium aerogenes (Escherich) Chester, are recognised.