Abstract
The aromatic polyketide antibiotic oxytetracycline (OTC) is produced by Streptomyces rimosus as an important secondary metabolite. Enhancement of self-resistance is one effective way to improve antibiotic production in Streptomyces spp. In the present study, we aimed to improve the production of OTC by introducing extra copies of the OTC resistance genes, otrA and otrB, into the chromosome of the industrial strain of S. rimosus (SRI). First, otrA and otrB were cloned and ligated with pSET152 to generate the recombinant plasmids pSET152-otrA/otrB, the demethylated pSET152-otrA/otrB by Escherichia coli ET12567(pUZ8002) were then introduced into SRI to yield otrA/ otrB knock-in mutants: SRI-A (otrA) and SRI-B (otrB). Ten selected mutants and the parent SRI strain were cultured in shake flasks. Production of OTC was increased by 67% in one SRI-B mutant compared with the parent strain, suggesting that the enhancement of resistance gene otrB in the antibiotic producer is an effective way to improve OTC biosynthesis. However, introduction of extra copy of otrB could retard growth of mutant cells.
Highlights
Introduction of Extra Copy of OxytetracyclineResistance Gene otrB Enhances the Biosynthesis of Oxytetracycline in Streptomyces rimosusXiaohe Chu1,2, Zijing Zhen1, Zhenyu Tang1, Yingping Zhuang1, Ju Chu1, Siliang Zhang1 and Meijin Guo1* 1State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, P.R
We aimed to investigate the influence of otrB knock-in mutants: SRI-A (otrA) and otrB on OTC production by introducing extra copies of these resistance genes into the genome of the industrial strain of S. rimosus (SRI)
The recombinant plasmids pSET152-otrA and pSET152-otrB were verified by XbaI and NdeI digestion (Figure 1A)
Summary
Introduction of Extra Copy of OxytetracyclineResistance Gene otrB Enhances the Biosynthesis of Oxytetracycline in Streptomyces rimosusXiaohe Chu, Zijing Zhen, Zhenyu Tang, Yingping Zhuang, Ju Chu, Siliang Zhang and Meijin Guo1* 1State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, P.R. We aimed to improve the production of OTC by introducing extra copies of the OTC resistance genes, otrA and otrB, into the chromosome of the industrial strain of S. rimosus (SRI). Production of OTC was increased by 67% in one SRI-B mutant compared with the parent strain, suggesting that the enhancement of resistance gene otrB in the antibiotic producer is an effective way to improve OTC biosynthesis. Many studies have reported the improvement of antibiotic production by engineering the availability of certain precursors in the producer organisms [4-6]. Other methods, such as the optimization of fermentation conditions, are available to regulate antibiotic production [7]
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