Essentially pure plasmids derived from Actinomycetes are described which have at least one restriction cleavage site for specific restriction enzyme and have molecular weight of less than 1.0.times.10.sup.7.
1. An isolated essentially pure plasmid derived from Actinomycetes having at least one restriction cleavage site for specific restriction enzymes and a molecular weight of less than 1.0.times.10.sup.7, wherein said plasmid is selected from the group consisting of pSF765, pSF619 and pSF689.
2. The plasmid according to claim 1 which is pSF765.
3. The plasmid according to claim 1 which is pSF619.
4. The plasmid according to claim 1 which is pSF689.