Factors affecting the growth and behaviour of axenic strains ofEntamoeba invadensRodhain, 1934

Abstract

1. Axenic strains ofEntamoeba invadenscan be maintained indefinitely, by serial culture, in saline containing a slice of liver. Growth in this medium is poor, the amoebae are vacuolated, and few cysts are formed.2. The optimum concentration of NaCl for amoebic growth in this medium is 0·75–1·0%, and the optimum pH is 5·7–6·1.3. The source of the liver tissue in the medium is unimportant, but, of several tissues tested, liver was the only one which supported amoebic growth in serial culture.4. Suspensions of minced liver also supported amoebic growth, but the growth-promoting activity of the liver was removed completely by centrifugation, autoclaving, and Seitz- or glass-filtration. Heat treatment at 50–60° C. and prolonged storage at 8° C. partially inactivated the liver.5. Growth in axenic saline-liver medium does not affect the ability ofE. invadensto grow and undergo mass encystation when reassociated with suitable bacteria.