Virtually all of the polyphosphate (PP) present in yeast protoplasts can be recovered in a crude particulate fraction if polybase-induced lysis is used for disrupting the protoplasts. This fraction contains most of the vacuoles, mitochondria and nuclei. Upon the purification of vacuoles the PP is enriched to the same extent as are the vacuolar markers. The amount of PP per vacuole is comparable to the amount of PP per protoplast. The possibility that PP is located in the cell wall is also considered. In the course of the incubation necessary for preparing protoplasts, 20% of the cellular PP is broken down. As this loss of PP occurs to the same extent in the absence of cell wall degrading enzymes, it is inferred that internal PP is metabolically degraded, no PP being located in the cell walls. It is concluded that in Saccharomyces cerevisiae most if not all of the PP is located in the vacuoles, at least under the growth conditions used.

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A container system for rapid infection of roots with pathogenic or mycorrhizal fungi was used to test the effect of the two commercial biological control agents, Trichoderma harzianum and Streptomyces griseoviridis, on the formation of vesicular-arbuscular mycorrhiza in soybean. In the presence of these biocontrol agents, mycorrhiza formation with Glomus mosseae was significantly depressed, particularly with S. griseoviridis. Infection by the root pathogen Rhizoctonia solani was not altered by these agents. Remarkably, not only R. solani but also T. harzianum induced accumulation of large amounts of the phytoalexin glyceollin in the roots. In contrast, roots inoculated with S. griseoviridis or with the mycorrhizal fungus G. mosseae did not accumulate glyceollin.