Nitrogen-Fixing Spore-Forming Aerobic Bacteria Isolated from the Rhizosphere of Some Gramineous Plants in Western Japan

Abstract

Seven heat-resistant bacterial strains, which grew anaerobically in nitrogen-free medium and aerobically in nitrate-containing medium, were isolated from the rhizosphere soils of wheat, corn and Susuki (Miscanthus sinensis) grown in farms or grasslands in Hiroshima prefecture, western Japan. The cells of the isolated strains were rods, 0.4 to 1.0μm × 1.4 to 3.4μm, and formed ellipsoidal endospores. The guanine plus cytosine contents of these strains were 43.6 to 54.7mol%. The strains produced hydrogen and carbon dioxide from formate under anaerobic conditions, and the enzymes formate dehydrogenase and hydrogenase were rapidly inactivated when crude extracts were shaken under air.
Some properties of the isolated strains were compared with those of the strains of Paenibacillus polymyxa, P. macerans and P. azotofixans.