摘要
Since the first discovery of cyanobacterian plasmids in 1973, more than 60 strains have been found to have extra-chromosomal DNA, and their distribution covers almost all groups of the cyanobacteria. However, they were not discovered in the two unicellular genera Gloeocapsa and Gloeothece, and no further report was there on them ever since. Some species of these two genera having the ability to fix atmospheric nitrogen aerobically carry
