The Bacterial Flora of Distilled and Stored Water. I. General observations, techniques and ecology

A total of 36 samples of distilled water from 10 different sources were plated on salt-free agar, incubated at 20°C, and colonies of different appearance fished. Duplicate plates of selected samples were incubated at 37’C, Samples were also plated on agar with 1% NaCl added for study of incidence of psychrophils and halophobes. A number of plates were prepared from fresh river water, from such water stored in the laboratory for several weeks, and from distilled water to which a small amount of soil had been added. A few plates were also exposed directly to laboratory air. From the various plates were fished all colonies which appeared different; a total of 306 isolates was obtained. These cultures were studied morphologically, culturally and physiologically. The great majority of the distilled water isolates were Gram-negative, polar flagellated, nonfermentative straight rods. Sporeformers, cocci, typical spirilla, and fermentative bacteria were absent and the difference between the flora of distilled water on the one hand and river water and air on the other is striking. In addition to the usual types of bacteria, there were found several types of aggregating bacteria which are described in some detail.