Enhanced clavulanic acid production inStreptomyces clavuligerus NRRL3585 by overexpression of regulatory genes

We constructed four recombinant plasmids to enhance the production of clavulanic acid (CA) inStreptomyces clavuligerus NRRL3585: (1) plBRHL1, which includesccaR, a pathway-specific regulatory gene involved in cephamycin C and CA biosynthesis; (2) plBRHL2, containingclaR, again a regulatory gene, which controls the late steps of CA biosynthesis; (3) pGIBR containingafsR-p, a global regulatory gene fromStreptomyces peucetius, and (4) pKS, which harbors all of the genes (ccaR/claR/afsR-p). The plasmids were expressed inS. clavuligerus NRRL3585 along with theermE* promoter. All of them enhanced the production of CA; 2.5-fold overproduction for plBRHL1, 1.5-fold for plBRHL2, 1.6-fold for pGIBR, and 1.5-fold for pKS compared to the wild type.