The classification of rhizobia has been gone through a substantial change in recent years due to the addition of several new genera and species to this important bacterial group. Recent studies have shown the existence of a great diversity among nitrogen-fixing bacteria isolated from different legumes. Currently, more than 98 species belonging to 14 genera of αand βproteobacteria have been described as rhizobia. The genera Rhizobium, Mezorhizobium, Ensifer (formerly Sinorhizobium),

Root-nodulating bacteria were isolated and characterized from grain and forage legumes growing in Fez regions. A total of 110 Rhizobium strains were characterized on the basis of morphological, cultural, and phenotypical properties. Phenotypic characteristics studied included growth rates in various media, colony morphology, tolerances to extremes of temperature, salt and pH and resistance to different concentrations of heavy metals and antibiotics. The isolates were very diverse phenotypically. Eighty seven of isolates were fast growing rhizobia. Thirty four strains tolerated high concentration of salt (2% NaCl). The majority of our isolates tolerated temperatures ranging between 20 and 37°C, but not above 55°C. Also, the isolated strains tolerated extreme pH in their medium from 4.8 to 8.8. The antibiotic resistance of these strains showed a high level of resistance against streptomycin, kanamycin, ampicillin, tetracycline, and chloramphenicol. The highest resistance to heavy metals was recorded for arsenate, copper, zinc, nickel, and mercury. Also, a moderate resistance was found for chromium. Polymerase chain reaction (PCR) method and 16S rRNA gene sequencing were used for the genotypic analysis of 17 Rhizobium strains selected on the basis of phenotypic study. The results showed a high diversity among the strains.

This study was conducted in order to evaluate the symbiotic effectiveness of Rhizobium strains isolated from food legumes (Bean) collected from different sites in Fez city and regions (Morocco). For this purpose, 15 isolates were obtained. Seeds were inoculated with these isolates and grown in bags containing sterile soil in greenhouse under controlled plant growth conditions. 30 days after planting several measurements were carried out to assess nodulation, plant growth and N 2 fixation. Nodule number and dry weight were determined as an indication of inoculation response; shoot and Root dry weights as an indication of growth response, and N-uptake as an indication of nitrogen fixation effectiveness. The results of the experiment were statistically analyzed showed a statistically significant difference between the tested strains (P < 0.05).

The present work aimed to evaluate the antibacterial activity of aqueous and methanolic extracts of Coriaria myrtifolia's leaves against Agrobacterium sp. and Agrobacterium tumefaciens "plant pathogen responsible for crown gall" in an objective to identify novel antimicrobial agents and to put forward efforts of proving plant's extracts scientific credibility, and determining their spectrum of activity. The bacteria tested were found profoundly sensitive to both of the C. myrtifolia extracts. The extent of inhibition was more important by methanolic extract than by aqueous one. The average diameter of inhibition zones ranged from 10.67 to 15.33 mm and 12.68 to 18 mm for aqueous and methanolic extract, respectively. This study was the first to report the antimicrobial activity of extracts obtained from the leaf of C. myrtifolia against Agrobacterium sp. and Agrobacterium tumefaciens. It can be concluded that the observed antibacterial characteristics of C. myrtifolia indicate that it might be a promising antimicrobial agent.