Isolation and identification of endophytic diazotroph from Cyndon dactylon

The nitrogenase activities of endophytic diazotrophs in Cyndon dactylon were studied by acetylene reduction assay (ARA). The results showed that 24 endophytic diazotrophs had been obtained using N-free medium. Significant differences in nitrogenase activities were observed among the endophytic diazotrophs, ranging from 3.45 to 383.05 μmol·h-1·mL-1. Nitrogenase from the strains of GC-1 had the highest activity. Nine strains with higher nitrogenase activity were identified as Klebsiella,Enterobacter,Pseudomonas,Pantoea and Rhizobium, respectively, by morphological, physiological-biochemical characterization and 16S rDNA sequence analysis.