Development of Integrated Vectors with Strong Constitutive Promoters for High-Yield Antibiotic Production in Mangrove-Derived Streptomyces .

It is important to improve the production of bioactive secondary products for drug development. The Escherichia coli-Streptomyces shuttle vector pSET152 and its derived vector pIB139 containing a strong constitutive promoter ermE p* are commonly used as integrative vectors in actinomycetes. Four new integrative vectors carrying the strong constitutive promoter kasO p*, hrdB p, SCO5768 p, and SP44, respectively, were constructed and proven to be functional in different mangrove-derived Streptomyces host strains by using kanamycin resistance gene neo as a reporter. Some biosynthetic genes of elaiophylins, azalomycin Fs, and armeniaspirols were selected and inserted into these vectors to overexpress in their producers including Streptomyces sp. 219807, Streptomyces sp. 211726, and S . armeniacus DSM 43125, resulting in an approximately 1.1-1.4-fold enhancement of the antibiotic yields.