Purpose The current study aimed to optimize the culture and production parameters of industrial production of lincomycin A by Streptomyces lincolnensis using a statistical approach that could also reduce unwanted by-products. Methods The Plackett-Burman design, steepest ascent method, and response surface design were used to evaluate different factors that affect lincomycin A production. Results Using an optimized S. lincolnensis fermentation medium, lincomycin A production was increased up to 4600 mg/L in shaking flasks, which indicated a 28.3% improvement over previous production in an un-optimized medium (3585 mg/L). Additionally, the concentration of lincomycin B by-product was reduced to 0.8%, which was 82.2% lower than that in the un-optimized medium. Further, quantitative real-time PCR analysis revealed the optimized medium improved lincomycin A production by stimulating key genes in the lincomycin A biosynthesis pathway, as well as an osmotic stress gene. Conclusions Based on the results, the sequential optimization strategy in this study provides powerful means for the enhancement of lincomycin A with less by-product. We found that osmotic stress reduced the concentration of lincomycin B, which could also help reduce fermentation by-product yields in other actinobacteria.

Demeclocycline (DMCTC), a tetracycline derivative antibiotic produced by Streptomyces aureofaciens, has attracted attention owing to its high bioavailability, prolonged maintenance of a therapeutic concentration, and greater efficacy against many infectious microorganisms. However, the productivity of the DMCTC-producing strains has remained low. Thus, it is necessary to identify gene-knockout or amplification targets to increase DMCTC production. Here, we demonstrated that ctcB, which encodes a Streptomyces antibiotic regulatory protein (SARP), and ctcC, which encodes a resistance gene, positively regulate the biosynthesis of DMCTC in S. aureofaciens strain DT1. In particular, overexpression of the ctcB gene in S. aureofaciens DT1 significantly enhanced DMCTC production, resulting in increased expression of ctcG, ctcN, ctcQ, ctcH, ctcV, and ctcC. The deletion of ctcB dramatically reduced the DMCTC level, implying that CtcB is an activator of DMCTC biosynthesis. Although overexpression of the ctcC, which encodes a ribosomal protection protein, enhancing DMCTC biosynthesis in S. aureofaciens DT1, the improvement was limited compared with that achieved by ctcB overexpression. This is the first study to identify the role of ctcB and ctcC in DMCTC accumulation; these genes may also be ideal candidate targets for facilitating DMCTC production by other Streptomyces strains.

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PurposeThe current study aimed to optimize the culture and production parameters of industrial production of lincomycin A by Streptomyces lincolnensis using a statistical approach that could also reduce unwanted by-products. MethodsThe Plackett-Burman design, steepest ascent method, and response surface design were used to evaluate different factors that affect lincomycin A production. ResultsUsing an optimized S. lincolnensis fermentation medium, lincomycin A production was increased up to 4600 mg/L in shaking flasks, which indicated a 28.3% improvement over previous production in an un-optimized medium (3585 mg/L). Additionally, the concentration of lincomycin B by-product was reduced to 0.8%, which was 82.2% lower than that in the un-optimized medium. Further, quantitative real-time PCR analysis revealed the optimized medium improved lincomycin A production by stimulating key genes in the lincomycin A biosynthesis pathway, as well as an osmotic stress gene. ConclusionsOptimizing the fermentation medium improved lincomycin A production and decreased that of the lincomycin B by-product, which could help cut production costs and simplify downstream separation processes. We found that osmotic stress reduced the concentration of lincomycin B, which could also help reduce fermentation by-product yields in other actinobacteria.