Phaseolus lunatus is nodulated by a phosphate solubilizing strain of Sinorhizobium meliloti in a Peruvian soils.

Ernesto Ormeño¹, Roxana Torres¹, Juan Mayo¹, Raúl Rivas², Encarna Velázquez², Doris Zúñiga¹

¹Laboratorio de Ecología Microbiana Marino Tabusso. Departamento de Biología. Universidad Agraria de la Molina. Lima. PERÚ.

²Departamento de Microbiología y Genética, Facultad de Farmacia, Universidad de Salamanca. SPAIN.

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The genus Phaseolus includes several species indigenous of American continent that belong to family Leguminosae. This genus includes several species, some of them only are cultivated in American countries. This is the case of Phaseolus lunatus in Peruvian soils. This plant can be nodulated for fast and slow growing rhizobia. But, until the moment the fast growing species nodulating Phaseolus commonly belong to genus Rhizobium and more rarely to Sinorhizobium fredii . In this work we have isolated several strains from Phaseolus lunatus growing in Peru soils and we analysed their ability to solubilize phosphate. A strain, LMTR32, showed a high ability to solubilize bicalcium phosphate from YED-P plates. The 16S rRNA sequence of this strain showed a 100% similarity with the type strain of Sinorhizobium meliloti. The LMW RNA profiles of this strain are identical to those of type strain of Sinorhizobium meliloti. Although more studies are necessary in order to establish the prevalence of this species in nodules of Phaseolus lunatus in Perú, this result coincides with those obtained in Canary Islands. In this case, more than one strain was identified as Sinorhizobium meliloti. Therefore, will be very interesting to study more wide populations of rhizobia nodulating Phaseolus in these two soils because according to our results there are differences among the species of rhizobia nodulating Phaseolus vulgaris in Canary Islands and peninsular soils in Spain.