Symbiotic effectiveness and bacteriocin production by Rhizobium leguminosarum bv viceae isolated from agricultural soils in Spain

A collection of twenty wild type strains of Rhizobium leguminosarum bv. viceae was obtained from five different agricultural locations in Granada (Spain) and tested with a commercial cultivar of faba bean (Vicia faba cv. Alborea) under monoxenic conditions of culture in Leonard jars, in order to study the diversity of symbiotic efficiency among local isolates in terms of nodulation and nitrogenase activity. There were large and significant differences in these symbiotic parameters between the rhizobial strains. Bacteriocin production of Nod(+) Fix(+) indigenous isolates of R. leguminosarum bv. viceae was also investigated. Strain Z25 characterized in this study was one of the most effective isolates. according to nodule dry matter accumulation and total ARA results, and showed broad bacteriocinogenic activity on rhizobia, with a high potential to inhibit growth of other strains belonging to the biovar viceae, but not bacteria belonging to other genera. The bacteriocin is produced by strain Z25 under a wide range of culture conditions, and some of the properties of the active compound showed here (non-dialysability, sensitivity to heat and proteolytic enzymes) strongly suggest a proteinaceous nature. Strain Z25 appears to be a promising candidate for use as an inoculant under field conditions. (C) 1998 Elsevier Science B.V. All rights reserved.