Genetic engineering of an industrial strain of Streptomyces clavuligerus for further enhancement of clavulanic acid production

Authors : Aslihan Kurt KIZILDOĞAN, Güliz Vanli JACCARD, Alper MUTLU, İbrahim SERTDEMİR, Gülay ÖZCENGİZ

Pages : 342-353

View : 15 | Download : 9

Publication Date : 2017-12-01

Article Type : Research Paper

Abstract :An industrial clavulanic acid insert ignore into journalissuearticles values(CA); overproducer Streptomyces clavuligerus strain, namely DEPA, was engineered to further enhance its CA production. Single or multiple copies of ccaR, claR insert ignore into journalissuearticles values(pathway-specific activators);, and cas2 insert ignore into journalissuearticles values(CA synthase); genes under the control of different promoters were introduced into this strain. CA titers of the resulting recombinants were analyzed by HPLC in a dynamic fashion and compared to the vector-only controls and a wild-type strain of S. clavuligerus while their growth was monitored throughout fermentation. The addition of an extra copy of ccaR, under control of its own promoter or constitutive ermE* promoter insert ignore into journalissuearticles values(PermE*);, led to 7.6- and 2.3-fold increased volumetric levels of CA in respective recombinants, namely the AK9 and ID3 strains. Its highly stable multicopy expression by the glpF promoter insert ignore into journalissuearticles values(PglpF); provided up to 25.9-fold enhanced volumetric CA titers in the respective recombinant, IDG3. claR expression controlled with its own promoter or ermE* and glpF-mediated amplification in an industrial strain brought about only about 1.2-fold increase in the volumetric CA titers. An extra copy of cas2 integration with PermE* into the S. clavuligerus DEPA genome led to 3.8-fold higher volumetric CA production by GV61. Conclusively, multicopy expression of ccaR under PglpF can result in significantly improved industrial high-titer CA producers.
Keywords : Clavulanic acid, industrial Streptomyces clavuligerus, strain improvement, promoters, ccaR overexpression