BACILLUS-STEAROTHERMOPHILUS PLASMID PSTK1 REPLICON IS FUNCTIONAL IN ESCHERICHIA-COLI

A kanamycin-resistant plasmid possessing a thermostable replicon deriv ed from Bacillus stearothermophilus cryptic plasmid pSTK1 was construc ted. The plasmid could transform not only B. stearothermophilus and Ba cillus subtilis, but also Gram-negative Escherichia coli. The behavior of the plasmid in the hosts was examined. The plasmid was stably main tained even at 67 degrees C in B. stearothermophilus without selective pressure. During the plasmid replication, single-stranded DNA (ssDNA) intermediates were found in E. coli, while these were not found in B. subtilis.