Determination of Multiple Forms of Esterases in Rhizobium by Paper Electrophoresis

Summary: Fifty-two strains, comprising six Rhizobium species, were examined for their esterase patterns using electrophoresis on cellulose acetate. Esterase activity was detected in five Rhizobium species. The sixth species, R.japonicum, was characterized by the absence of esterase activity in all but one of the strains examined. Rhizobium trifolii and R. leguminosarum strains showed similarities in their esterase profiles. Rhizobium meliloti strains formed a group distinct from these on the basis of their esterase patterns. Rhizobium lotus sp. and R. phaseoli also exhibited esterase activity. Heat denaturation and metal inhibition studies suggest that the esterase activity is truly enzymic. The inability of the bacterial esterase to react with a synthetic peptide suggests that residual esterase activity associated with certain proteolytic enzymes is not involved. Heat tests revealed differences in the sensitivity of the multiple forms of esterases in rhizobia to inactivation.