Ref ID : 3796
Diana Menapace, D.A. Klein, J.F. McClellan, and J.V. Mayeux; A Simplified Overlay Plaque Technic for Evaluating Responses of Small Free-Living Amebae in Grassland Soils. J.Protozool. 22(3):405-410, 1975
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The responses of amebae and bacteria in a grassland soil were investigated by an overlay plaque technic developed in this laboratory. This procedure, using Aerobacter aerogenes as the food source, allowed convenient assay of significant changes in ameba populations which resulted from additions of nutrient and water. In comparison with controls, when water was added an initial increase occurred in bacterial counts followed by an increase in the numbers of amebae. Upon addition of glucose, ameba populations increased initially and then decreased with time, while populations of bacteria remained constant. The addition of hay resulted in significant increases in populations of bacteria and amebae. Plaque appearance on enumeration plates was most rapid with inocula from nutrient-treated soils. Predominant amebae recovered by this technic were species of Acanthamoeba and Hartmannella. They were estimated to be present in untreated soils at 3.2x10E3/gram. Ameba feeding experiments were used to evaluate the possible suitability of other bacteria as food. The results indicated that nonpigmented laboratory strains of bacteria were preferred, while pigmented grassland isolates were more rapidly utilized. Small soil amebae appear to be sensitive to minor spoil perturbations, and the enumeration procedure developed in this study should aid in following their responses to environmental stresses.