Isolation, Enumeration and Identification of Amebae from a Nebraska Lake*

Abstract

SYNOPSISA plaque technic was evaluated and used for the isolation and enumeration of small, free‐living amebae in lake‐bottom samples which were collected each month for one year from a Nebraska lake. Several culture media were evaluated, and a simple glucose‐salts medium was chosen. The most frequent ameba in the lake‐bottom samples was Acanthamoeba polyhaga which underwent marked increases and decreases in population densities during the collection period. This pattern was not correlated with water temperature, bacterial counts, and nitrate or phosphate levels. Other species of amebae of the genera Hartmannella, Vahlkampfia, Naegleria, Paratetramitus and Echinamoeba were isolated. Most of these were either found infrequently or remained at relatively low, constant densities throughout the year. In addition, 4 species of Acrasieae of the genera Dictyostelium and Polysphondylium were isolated from the lake‐bottom samples.