Isolation and Diagnosis of Rhizobium Bacteria Isolated from The Root Nodules of Leguminous Plants and Studying Their Plasmid Content.

The study included thirty-six isolates of rhizobia bacteria were isolated from the nodules located on the roots of nine types of leguminous family plants that were planted in four areas of the city of Mosul for the winter agricultural season for the year 2020-2019, where they studied the phenotypic and agricultural characteristics of the isolated bacteria in addition to a study of resistance and sensitivity to the isolates of rhizobia bacteria. The study included ten antibiotics, and resistance ratios differed between isolates groups, where the highest resistance rate for residual bacteria isolates was 100% for Nystatin and Amoxicillin, and the lowest resistance was for Tetracycline and Streptomycin, as it reached 22.2%. As for the rest of the antibiotics, there is a difference between that . As for heavy metal salts, all the isolates of rhizobia bacteria under study were resistant to both CdCl2 chloride and CoCl2 cobalt by 100%, while their resistance to nickel chloride NiCl2 was 77.7% and the lowest resistance to heavy metal was mercury chloride HgCl2, reaching 33.3%. The plasmid DNA content was described for the studied isolates, as the results showed that there are two types of plasmid DNA bundles, the first type close to large-scale gel drilling called Mega plasmid represents symbiotic plasmids that carry the genes of contract formation and nitrogen fixation and the second type moves far from the gel drilling and they are sizes small equal representing non-symbiotic plasmids.