Abstract
Summary Ten experimental media, each of which contained products of T. cruzi metabolism and some of which contained, in addition, T. cruzi rendered immotile and nonviable by various procedures, were evaluated for their ability to maintain growth of E. histolytica. Other studies of the media, paralleling the foregoing, provided comparative data relative to their oxygen uptake and their efficacy in the reduction of methylene blue. The media were also studied for evidence of acid production by treated organisms. The resultant data showed that abundant growth of ameba occurred with untreated T. cruzi, and some growth occurred with treated T. cruzi that exhibited no oxygen uptake, were immotile and incapable of reproduction, but which exhibited activity in the reduction of methylene blue and produced acid. However, when T. cruzi were separated from the ameba by a cellophane membrane or removed from the conditioned medium, and when the metabolic activity of T. cruzi was completely inhibited, no growth of the ameba occurred. The data suggest the dependence of E. histolytica on the metabolism of its associates and indicate thereby the probable area wherein lies the identity of the contribution by the associates to growth of the ameba.
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