The Enumeration of Waterborne Bacteria by a New Direct Count Method

SUMMARY: A direct method has been devised to enumerate bacteria in lake water, using a concentration technique. The method involves the staining of 10 −2 ml samples of water with gentian violet dissolved in a glycerol‐water base, and concentrating in vacuo . The residue remaining after concentration consists of glycerol and stained bacteria. Glass capillaries are filled from the concentrate and the volume of the contents determined. The organisms in this are counted microscopically. Results by the direct count were from six times to eleven thousand times greater than by the colony count.