Morphological characterization of the native strain of Rhizobium sp. obtained from the root nodules of the pea crop (Pisum sativum L.) pink variety in the canton Espejo province of Carchi

Abstract

Nitrogen-fixing bacteria and legumes maintain a symbiotic relationship that allows them to obtain nutrients efficiently, however, there is little information on the morphological characteristics and adequate conservation medium of the bacteria that nodulate in the root system of the pink variety of pea. (Pisum sativum L.). The objective of this research was to isolate and conserve native strains of Rhizobium sp., From the root nodules of the pea crop, a pink variety, for which the field pea cultivation was established in the Espejo canton, Carchi province. To obtain the nodules in the field, a random zigzag sampling of young and vigorous plants in the phenological stage of flowering was carried out. 3 plants were taken at 5 sampling points, for a total of 15 plants from the lot. The nodules obtained were taken to the laboratory and planted in Yeast Mannitol Agar with Bromothymol Blue (YMA + AB). The native strains of Rhizobium were morphologically characterized, where colonies of circular, convex shape with entire edge and smooth surface, of a creamy-pink white color and gelatinous consistency were observed, and by means of Gram staining, Gram negative bacilli were reported. carried out the biochemical characterization, where it was possible to identify the native strain of Rhizobium, due to its positive reaction to the Biuret test, resistance to 2% NaCl, and inability to produce H2S, typical characteristics of rhizobia strains. Furthermore, an essential element in the identification was the lack of absorption of the Congo red dye. The isolated strain was preserved in YMA + AB medium, and then incubated at 30 ° C for 5 days and, under aseptic conditions, the strain was placed in a refrigerator at a temperature of 4 ° C, to preserve the genetic integrity of the microorganism.