Inhibition of Nitrogen‐Fixing and Nitrifying Bacteria by Seed Plants

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Abstract
Euphorbia suinna occurs in the pioneer weed stage of succession in abandoned fields in several midwestern states of the United States. It was previously found to be very inhibitory to several test strains of nitrogen-fixing and nitrifying bacteria and to several associated seed plants. The present project was concerned wilh the identification of the chief inhibitors produced by that species, using appropriate column and paper chromatographic techniques, and by tests of bacterial inhibition employing the diffusion technique on solid media. Three hydrolyzable tannins were consistently isolated from extracts of the species. All three tannins and purified reagent tannic acid from at least two commercial sources yielded ellagic acid, gallic acid, and glucose on hydrolj'sis by acid or tannase. All yielded one or more additional phenolics which were not identified. The tannins from E. supina were all slightly different from each other and from commercial reagent tannic acid as indicated by different Rf's on paper, elution sequence from polyamide columns, and relative amounts of glucose, ellagic acid and gallic acid produced on hydrolysis.