Caractérisation phénotypique et génotypique des bactéries nodulant la légumineuse du genre Phaseolus

Abstract

The symbiosis Rhizobium-legumes is a natural process, which can benefit the plant by the assimilation of atmospheric nitrogen. In Algeria, beans or Phaseolus are leguminous plants that play a prominent role in human nutrition, thanks to its protein and carbohydrate value, and for its economic value for the country and the citizen. In order to improve the outcomeof this legume, 86 isolates were collected from the root nodules of two species of Phaseolus; P. vulgaris and P. coccineus grown in five orchads located in Eastern and Northeastern Algeria. These isolates are characterized by a phenotypic study (physiological, biochemical and nutritional tests) with the reference strains, which gives a description comparing withRhizobium. Also our isolates present a positive reaction to direct contact with the bacteriophages, that permits their use as markers for the identification of bacteria. A nodulation test under bacteriologically controlled conditions is carried out by demonstrating the ability of the isolates to nodulate the roots of the host plant which has shown the formation of white nodules, indicating that our isolates are infectious and they (This formation) confirm the symbiotic relationship between the host plant and the microsymbion which is a specific relationship. The molecular study carried out confirmed the belonging of the T8 isolate to the Bacillus subtilis species with a similarity of 98%.