Strain-specific antigens in Rhizobium leguminosarum.

Fifty strains of Rhizobium leguminosarum, isolated from five species of host plant (Pisum sativum, P. arvense, Vicia sativa, V. faba, and a Lathyrus sp.) were examined for the presence of strain-specific somatic antigens by immune-diffusions against 13 antisera. Thirty eight strains (76 per cent) were found to belong to the same sero-group and were serologically indistinguishable from each other, but four of these strains also exhibited non-reciprocal cross reactivity with other antisera. In contrast to this, five Australian strains, isolated from P. sativum, showed a high degree of strain specificity.