Abstract
A system for genetic exchange in Rhodopseudomonas capsulata has been discovered. Each genetic marker thus far examined can be transferred, and many strains of Rps. capsulata can participate in genetic exchange. The mechanism of gene transfer seems unlike that of any previously described bacterial system, since genes can be transferred by cell-free filtrates, but the vector is resistant to deoxyribonuclease and has a sedimentation constant of about 70 S.