Isolation of Nitrogen-Fixing Bacteria from Gramineous Crops and Measurement of Nitrogenase Activity

For researching nitrogen-fixing bacteria associated with gramineous crops, wecollected growing roots of rices, wheats, oats, barleys, ryes, and maizes at 10 sites of southern Korean peninsula. Endophytes and free living bacteria were isolated from those crop roots. Sixty-three isolates were classified on the basis of different morphology, size, color, host of colony, and the 16S rDNAs sequence. The analyses ofPCR amplification for nifH gene and nitrogenase activity assay, revealed that all isolates contained nitrogen-fixing abilities. In addition, most of them have cellulase activity which is one of the common features of endophytic bacteria from plant.