Isolation, Characterization and Identification of Salt Tolerant Nitrogen Fixing Bacteria

Abstract

The present investigation deals with the isolation and characterization of nitrogen-fixing bacteria (NFB) such as Azotobacter sp. and Azospirillum sp. from paddy field rhizosphere of Damietta governorate, Egypt. Twelve Azotobacter spp. and 12 Azospirillum spp.Were identified based on morphological and physiological characteristics. All isolates were tested for salt tolerance. The highest salt tolerant of Azotobacter spp. Were S2-8, S3-3, S1-3, S3-2, whil they S2-11, S1-1, S5-1, S3-6 in case of Azospirillum spp. were. Nitrogenase activity assay of the highest nitrogen fixing isolates was (S2-8) in case of Azotobacter sp. and (S2-11)in case of Azospirillum sp. Molecular identification showed that isolates were Azotobacter chroococcum and Azospirillm brasilense. Based on this study salt-tolerant isolates of Azotobacter chroococcum and Azospirillm brasilense could be highly used in cultivation of paddy soil in coastal environment.