FIG. 3.

Construction and analysis of an H. volcanii hv54h-knockout strain. The chromosomal (chr) copy of hv54h was replaced with hv54h interrupted by the H. hispanica mevinolin resistance gene (mevR) in H. volcanii strain WRHv-6c (harboring the hv54h•6xhis expression plasmid pWR6-c), creating strain WRHv-6c/54KO (a). This strain and a control strain (WRHv-6c) were then examined as to whether they could be cured of pWR-6c in the absence of antibiotic (novobiocin) selection for the plasmid (b). At each indicated transfer, cells cultured in the absence of novobiocin were grown on RM supplemented with novobiocin. Error bars represent standard deviation. Student's paired t test was used to generate P values for each indicated transfer (T): P ≪ 0.0001 for T3, T9, T12, and T15; P = 0.012 for T6. nbR, novobiocin resistance gene.