Abstract

Characterization of Indigenous RhizobiumStrain Isolated from lentil in Rajshahi, Bangladesh

Rhizobium spp. was isolated from root nodules of lentil (Lens culinaris L.), and itsmorphological, cultural, physiological and biochemical characteristics were studied. It was observed that the colonies were circular, light pink, convex, entire and opaque. The bacterium was gram negative, rod shaped, aerobic, non-spore forming and motile. Isolates were positive for Catalase,Citrate utilization test, Urea hydrolysis, Congored test, Nitrification test,Oxidase test, Triple sugar iron test, MacConkey agar testand, Motility tests. The samples were found negative for Methyl Red (MR), Voges-Proskauer(VP), Indole, Starch hydrolysis test, Hydrogen-sulfide production and Hofer’s alkaline test. The isolate can fermentsucrose, glucose, fructose, mannitol and produce acid. Screening for antibiotic resistance in this study revealed that the strain were resistant to Ampicilin, Erythromycin, Gentamicin, Amoxycillin, Penicillin, Streptomycin and Nalidixic acid. The isolate grew optimally at pH 7.0 and temperature 28 ??C. Moreover, the isolate was sensitive to the higher concentration of NaCl (>1%). Based on 16S rDNA sequence, the isolate was identified as Rhizobiumsp. SOY12strain. The results also revealed that Rhizobial inoculation in-duced significant changes in plant growth characteristics.

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