Isolation and Biochemical Characterization of Rhizobium Leguminosarum bv. Trifolii and Sinorhizobium Meliloti using API 20 NE and API 20 E

摘要

The present study was carried out to isolate and to investigate biochemical characteristics of twenty rhizobacteria strains from red clover ( Rhizobium trifolii ) and alfalfa ( Sinorhizobium meliloti ). The result of the study showed a low diversity in morphological, physiological and symbiotic properties among the rhizobial strains. Phenotypically all isolated strains had the same colony morphology conical with a smooth margin, the color and texture was watery to translucent. The isolates were fast-growing and failed to absorb Congo red. API 20NE and API 20E showed a negative reaction for the reduction of nitrate in RtS1, RtR2, and positive for SmM1, SmM2. The reaction was positive for ?2-galactosidase, ?2- glucosidase and negative for urease, arginine dihydrolase, for all rhizobial isolates. Carbon sources: glucose, arabinose, mannose,mannitol, maltose, were also positive for all strains. Rhizobial strains utilized a wider range of carbohydrates and this may be a helpful tool for the characterization of the isolates.