Isolation and characterization of native Rhizobiums strains from agricultural soils of Bonaft-Dize Yazd
Subject Areas : Biotechnological Journal of Environmental MicrobiologyAmir Mohammad Heydarinia 1 , Mehrane Heydarinia 2
1 - Department of Biology, Ashkzar Branch, Islamic Azad University, Ashkzar , Iran
2 -
Keywords: Rhizobia, symbiosis, leguminous plants, nitrogen fixation, PHB, bioplastics,
Abstract :
This study aimed to isolate and characterize indigenous rhizobia from the root nodules of legumes in agricultural soils, with a focus on their potential for symbiotic nitrogen fixation and bioplastic production. Root nodules were surface-sterilized using a sequential wash with sterile distilled water and 0.1% mercuric chloride solution. The sterilized nodules were then crushed, and the contents were streaked onto yeast extract mannitol agar (YEMA) plates and incubated at 28°C for up to seven days. Isolated colonies were examined for characteristic mucoid morphology, which is indicative of exopolysaccharide production.
Gram staining confirmed the isolates were Gram-negative rods. Furthermore, Sudan Black B staining revealed intracellular black granules with transparent centers, confirming the presence of poly-β-hydroxybutyrate (PHB), a precursor for bioplastics. The optimal growth conditions for the isolates were determined to be 25-30°C and a pH of 6-7. This research highlights the dual potential of native rhizobial strains: their application as biofertilizers to enhance soil fertility through symbiotic nitrogen fixation and their use as a sustainable source for the production of biodegradable plastics. Further investigation into the biodiversity of these indigenous strains is warranted to fully exploit their agricultural and industrial applications.
1-Glick, B. R., & Pasternak, J. J. (2003). Molecular biotechnology: Principles and applications of recombinant DNA (3rd ed.). ASM Press.
2-Somasegaran, P., & Hoben, H. J. (1994). Handbook for rhizobia: Methods in legume-Rhizobium technology. Springer-Verlag.
