The growth of an axenic strain ofEntamoeba invadensin different media

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Abstract
The growth of an axenic strain of Entamoeba invadens in two media (Trypticase–liver broth and Trypticase–Panmede) is compared with that of a monobacterial strain in diphasic medium supplemented with starch. The axenic strain multiplied more slowly, and produced lower yields of amoebae than the monobacterial strain.Amoebae multiplied more rapidly and produced higher yields in Trypticase–liver broth than in Trypticase–Panmede.The effect of certain variations in the basic Trypticase–Panmede medium was investigated. Serum stimulated the growth of the axenic strain in Trypticase–Panmede, so that although the initial multiplication rate was not increased, the maximum yields of amoebae were increased to levels that varied according to the concentration of the serum.The multiplication of the axenic amoebae was depressed by procedures which probably aerated the medium.I thank Dr L. S. Diamond for axenic strain NIH:200 of E. histolytica, and Professor E. Meerovitch for axenic strain PZ of E. invadens. I am much indebted to Dr P. Whittlestone, of the Department of Animal Pathology, Cambridge, who examined cultures of strain N for the presence of mycoplasmata. The work was carried out while the author was a member of the scientific staff, Medical Research Council.