Isolation and characterization of endophytic rhizobium sp. bacteria from wild legume plants collected in the Kirşehir region

In this study, Rhizobium sp. strains were isolated from wild leguminous plants chickpea (Cicer arietinum L.), vetch (Vicia cracca L.), and yellow sweet clover (Melilotus officinalis L.) collected from various districts of Kırşehir Province (Akçakent, Akpınar, Boztepe, Çiçekdağı, Kaman, and Mucur). For the identification and characterization of the isolates, morphological and physiological (Gram staining, motility), biochemical (catalase and oxidase tests), and cultural characteristics (growth on Bromothymol Blue Yeast Mannitol Agar, Congo Red Yeast Mannitol Agar, Peptone Glucose Agar, and Litmus Milk medium) were examined. Based on growth characteristics on YMA, Bromothymol Blue YMA, and Congo Red YMA media, 78 isolates were found to be consistent with the characteristics reported in the literature, whereas 31 isolates showed inconsistencies. All 78 isolates exhibiting favorable cultural characteristics were rod-shaped, and among them, 32 were determined to be Gram-negative. These findings are in accordance with the cytological features typically associated with the genus Rhizobium. Catalase, oxidase, and motility tests conducted on the 32 consistent isolates revealed that all of them were positive for these three parameters. Finally, in the growth test performed on Litmus Milk medium, 22 isolates exhibited an alkaline reaction and formed a serum zone. Keywords: Rhizobium sp., Nitrogen fixation, Legumes, Cicer, Clover, Vetch