Summary Introduction We have been studying the interrelation between R. capsulatus and other various microorganisms, in which there are symbiotic relationships (I). When R. capsulatlls and Az. vinelandii co-existed, molecular nitrogen was fixed much more than in each pure culture and many slime substances (polysaccharides, muco-polysaccharides etc.) were produced (2). In order to study symbiotic nitrogen fixation between the two microorganisms, first, the nature of the cell wall of both bacteria has to be known.