Utilization of the Salts of Organic Acids by the Colon-Aerogenes Group

The sanitary importance of the colon bacillus and its allies has led to numerous attempts to classify this complex group of bac-teria, for the possible existence of certain types within the group which might be of especial sanitary significance has long been recognized. Among the various biochemical tests usually applied to the study of bacterial groups, the qualitative fermentation of carbohydrates and higher alcohols has for many years held the most prominent place and the list of the substances so employed has been an ever lengthening one as new products have been made available. The list of non-nitrogenous carbon-containing com-pounds which may be utilized as sources of energy need not be limited, however, to the commoner carbohydrates and higher alcohols since it is known that some microorganisms possess the ability to break down a great variety of carbon-containing sub-stances of diverse structure. The present investigation was undertaken as a study in bacte-rial nutrition to gain some idea of.the utilization of the salts of the commoner organic acids by members of the colon-aerogenes group. Furthermore, should any separation of the various types within the group be effected, it was desired to determine whether this might be correlated with the distribution of these organisms in nature and therefore offer a possibility of practical use in the estimation of the sanitary quality of water. There are many scattered references in the literature on the utilization of organic acids, or their salts, by various bacteria, and some attempts have been made to formulate systems of classifi-