The Comparative Growth Cycle of Different Strains of Endamoeba histolytica in Transparent Medium and of the Same Strain in Different Media

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Abstract
Growth of the clones of 3 strains of E. histolytica (nos. 19, 22 and NRS) was studied in Shaffer-Frye medium. While amebae of strains 19 and 22 grew at a similar rate, those of NRS consistently failed to survive in these cultures for more than a few transfers. The population growth of strain 22 in Shaffer-Frye medium was compared with that of these amebae in diphasic and monophasic culture media with associated bacteria, without and with starch. In Shaffer-Frye medium the growth cycle fails to follow the same pattern as that in the other media. In the former the population increased rapidly during the first 48 hrs., remained somewhat stationary up to 96 hrs. and then decreased very slowly. In the latter, the amebic population growth curve approximated that reported for typical bacterial growth. Repeated expts. with culture tubes and flasks containing the same amount of medium and inoculated with the same size of inoculum showed that an increase in bottom surface area of the culture vessels enhances significantly the population growth of amebae in Shaffer-Frye medium, whereas no significant increase occurs when additional vertical surface is provided.