Biochemical Characterization of fast - and Slow - Growing Rhizobia

Bacterial strains and growth conditions. Fast-growing soybean Rhizobium strains USDA 191, USDA 192, USDA 193, USDA 194, USDA 201, USDA 205, USDA 206, USDA 208, USDA 214, USDA 217, and USDA 257 were isolated from soil or nodules collected in the PRC (20). Slow-growing soybean rhizobium strains PRC 005, PRC 74, PRC 113-2, PRC121-6, PRC 2031, and PRC B15, were oHtained from T. S. Hu, Institute of Soils and Fertilizers, Chinese Academy of Agricultural Sciences, Beijing, PRe. Bradyrhizobium japonicum strains USDA 6, USDA 31, USDA 34, USDA 74, USDA 94, USDA 110, USDA 122, USDA 123, USDA 136, USDA 138, USDA 142, and Y1, Y1a, Y2, Y2a, Y3, K2, K2a, SI, and Sla, were from the United States Department of Agriculture Culture Collection, Beltsville, Md. Rhizobium lupini CC814s and NZP 2037, Rhizobium leguminosarum Nitragin 92A3, Rhizobium phaseoli NZP 5097, and Rhizobium trifolii NZP 560 were obtained from R. M. Greenwood, Department of Scientific and Industrial Research, Palmerston North, New Zealand. R.leguminosarum HI 5-0 was isolated in Hawaii (30). R. leguminosarum 6015(pJB5JI) was obtained from P. Hirsch, Max Planck Institut, K61n, Federal Republic of Germany; R. phaseoli Bel 7.1 was obtained from E. L. Schmidt, University of Minnesota, Minneapolis; Rhizobium sp. (G. max cv. Peking), but formed ineffective symbioses with most commercial soybean culti-" vars .(20). In this study we used a serie~ of .diagnostic tests to examine the fast-growing, acid-producing PRC isolates for their relatedness to each other, to typical slow-growing R. japonicum strains, and to other fast-growing rhizobia. Biochemical Characterization of fastand Slow-Growing Rhizobia That Nodulate Soybeans