Improved production of clavulanic acid by reverse engineering and overexpression of the regulatory genes in an industrial Streptomyces clavuligerus strain

• DOI: 10.1007/s10295-019-02196-0
• Publication Date: 2019-06-04T16:08:22Z
• Authors: Hang Soo Cho; Jin Chul Jo; Chang-Hun Shin; Namil Lee; Joon-Sun Choi; Byung-Kwan Cho; Jung-Hye Roe; Chan-Wha Kim; Ho Jeong Kwon; Yeo Joon Yoon
• Keywords: Streptomyces clavuligerus; Metabolic Engineering; Strain (injury); Industrial fermentation; Streptomycetaceae

Abstract Genomic analysis of the clavulanic acid (CA)-high-producing Streptomyces clavuligerus strains, OL13 and OR, developed through random mutagenesis revealed a frameshift mutation in the cas1 gene-encoding clavaminate synthase 1. Overexpression of the intact cas1 in S. clavuligerus OR enhanced the CA titer by approximately 25%, producing ~ 4.95 g/L of CA, over the OR strain in the flask culture. Moreover, overexpression of the pathway-specific positive regulatory genes, ccaR and claR, in the OR strain improved CA yield by approximately 43% (~ 5.66 g/L) in the flask. However, co-expression of the intact cas1 with ccaR-claR did not further improve CA production. In the 7 L fermenter culture, maximum CA production by the OR strain expressing the wild-type cas1 and ccaR-claR reached approximately 5.52 g/L and 6.01 g/L, respectively, demonstrating that reverse engineering or simple rational metabolic engineering is an efficient method for further improvement of industrial strains.