Electrophoretic Properties of Fast- and Slow-Growing Species of Rhizobium

The electrophoretic mobility of Rhizobium trifolii strain TAl was relatively constant during the early and late phases of growth, but exhibited a temporary sharp increase in the late logarithmic--early stationary phase. The electrophoretic behaviour of slow-growing species of Rhizobium was characterized by zero mobility at pH 2· 0, and a constant negative mobility between pH 4·0 and 10·7. In contrast, all fast-growing strains, except R. trifolii TAl, exhibited slight positive mobility at pH 2· 0, a constant negative mobility between pH 4·0 and 9· 2, and a marked increase in mobility between pH 9·2 and 10·7. These results suggest that the surfaces of the slow-growing bacteria and strain TAl contain only acidic (carboxyl) groups, whereas those of the fast·growing strains contain a predominance of acid groups along with some basic (amino) groups.