Studies on Freshwater Bacteria: Effect of Medium Composition and Method on Estimates of Bacterial Population

Abstract

Summary. The effects of various inorganic and organic components used in media for estimating numbers of freshwater bacteria were determined. The inorganic elements appeared to affect the count obtained more than did the organic components. Of the media tested, none could support growth better than the CPS medium of this laboratory. The casein and glycerol concentration was optimal and variation in other organic components had little effect on counts. The surface spread plate was the most suitable method of estimating viable numbers and the effect of numbers of colonies counted on the distribution obtained is discussed.