ISOLATION AND IDENTIFICATION OF SOME RHIZOBIAL BACTERIA FROM FABA BEAN PLANTS UNDER EGYPTIAN SOIL CONDITIONS.

Legumes are the most important source of human food and forage. Legumes are able to provide the benefits of nitrogen fixation thanks to a strain of soil bacteria. Faba bean is the most important food legume. Moreover, it plays an important role in sustaining the productivity of the farming system through fixation of atmospheric nitrogen. Sixteen rhizobial isolates were collected from the root nodules in various locations under different soil conditions. Data indicated that most of the obtained isolates were superior compared to reference strains used. All rhizobial isolates tested were fast growing on YEMA medium, non-capsulated, short rods, Gram negative and motile. Cell size ranged from 1 to 4 mm. According to various NaCl Concentrations (from 0.0 to 6.5%), most of the tested isolates have a positive growth up to 4.5%, but both isolates K-ISORH7 and K-ISORH15 gave good growth at 6.0% NaCl Concentration. The most potent isolates were K-ISORH7 and K-ISORH15 which recorded highest number of nodules (172, 188) for faba bean variety V1 and (122,125) for V2, nodules dry weight (597, 607) mg per plant for V1 and (395 ,607) mg per plant with V2 ,in the same order as compares to all tested isolates and strains. It took the same trend for the rest of parameters. Genetically, according to 16S rRNA sequence, isolates were identified as Rhizobium sp. By 100% similarity with HR7(KM276562) and strain SEMIA 439 (MH236581) for K-ISORH7 and K-ISORH15 respectively with accession numbers LC431741 and LC431742 in the same order.