AN AUTONOMOUSLY REPLICATING TRANSFORMING VECTOR FOR SULFOLOBUS-SOLFATARICUS

A plasmid able to transform and to be stably maintained both in Sulfol obus solfataricus and in Escherichia coli was constructed by insertion into an E. coli plasmid of the autonomously replicating sequence of t he virus particle SSV1 and a suitable mutant of the hph (hygromycin ph osphotransferase) gene as the transformation marker. The vector suffer ed no rearrangement and/or chromosome integration, and its copy number in Sulfolobus was increased by exposure of the cells to mitomycin C.