Caracterización de Rhizobium spp. a partir de trébol violeta (Trifolium pratense) en cuatro localidades del cantón Ambato-Tungurahua

Abstract

Nitrogen is the most important nutrient for plant growth, legume crops are highly dependent on nitrogen fixed by nitrogen-fixing rhizobial bacteria. The identification and characterization of rhizobia indigenous to a particular area is the basis for the formulation of inoculants for sustainable legume production in the face of climate change. Rhizobium spp. were isolated from 4 localities of Ambato canton. The isolated bacteria were grown on Yeast Extract Agar medium and YMA mannitol with Congo red. The colonies were observed after 36-48 hours of incubation at 37 degrees Celsius, control plates showed growth of different microorganisms, while the isolation plates did not show contamination. A total of 88 isolates were obtained, characterized as rod-shaped, aerobic, non-spore-forming and motile. The isolates showed a milky pink color, were positive for methyl red, Voges-Proskauer, catalase, starch hydrolysis and motility on SIM agar. They were negative for the triple sugar iron test, negative for sulfuric acid production and negative for the indole test on SIM, while the Simmons citrate test was negative for 3 strains. The polymorphisms evaluated by UPGMA allowed establishing that the diversity of rhizobia had 76 percent similarity, grouping slow-growing rhizobia in the northern zone and fast-growing rhizobia in the southern zone of Ambato.