Enhancement of FK520 production in Streptomyces hygroscopicus by combining traditional mutagenesis with metabolic engineering

Yin

et al. 2020

Preprint

Background: Ascomycin is a multifunctional antibiotic produced by Streptomyces hygroscopicus var. ascomyceticus. As a secondary metabolite, the production of ascomycin is often limited by the shortage of precursors during the late fermentation phase. Polyhydroxybutyrate is an intracellular polymer accumulated by various microorganisms. The development of polyhydroxybutyrate as a useful carbon reservoir for precursor synthesis is of great significance for improving the yield of ascomycin.Results: The fermentation characteristics of the parent strain S. hygroscopicus var. ascomyceticus FS35 showed that the accumulation and decomposition of polyhydroxybutyrate were respectively correlated with the growth of strain and the production of ascomycin. The co-overexpression of exogenous polyhydroxybutyrate synthesis gene phaC and native polyhydroxybutyrate decomposition gene fkbU increased both strain biomass and ascomycin yield. Comparative transcription analysis showed that the storage of polyhydroxybutyrate during the exponential phase accelerated biosynthesis processes by stimulating the utilization of carbon sources, and the decomposition of polyhydroxybutyrate during the stationary phase increased the biosynthesis of ascomycin precursors by enhancing metabolic flux of primary pathways. The comparative analysis of cofactor concentration reflected that the biosynthesis of polyhydroxybutyrate depended on the supply of NADH pool. Under the condition of low sugar content in the later exponential phase, the optimization of carbon source addition further strengthened the polyhydroxybutyrate metabolism by increasing total concentration of cofactors. Finally, in the fermentation medium with 22 g/L starch and 52 g/L dextrin, the ascomycin yield of co-overexpression strain was increased to 626.30 mg/L, 2.11-fold higher than that of parent strain in the initial medium (296.29 mg/L). Conclusions: This paper reported for the first time that the polyhydroxybutyrate was beneficial to the growth of strain and the production of ascomycin by working as an intracellular carbon reservoir, storing as polymers when carbon sources are abundant and depolymerizing to monomers for the biosynthesis of precursors when carbon sources are insufficient. The successful application of polyhydroxybutyrate in increasing the output of ascomycin provided a new strategy for the high yield of other secondary metabolites.

Section: The Mechanism Underlying the Promoting Effect Of Polyhydroxymentioning

confidence: 60%

Section: The Mechanism Underlying the Promoting Effect Of Polyhydroxymentioning

confidence: 99%

Section: Measurements Of Fermentation Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Increasing Ascomycin Yield in Streptomyces Hygroscopicus var. Ascomyceticus by Using Polyhydroxybutyrate as an Intracellular Carbon Supply Station

Yin

et al. 2020

Preprint

“…FK523 is the main impurity in the production of FK520, resulting from the assembly of methylmalonyl-CoA onto the C21 position of the macrolide skeleton instead of the specific precursor ethylmalonyl-CoA [32]. To rule out competitive use of these precursors by for by-product synthesis, the yield of FK523 and the FK523/FK520 ratio in the strains FS35 and OphaCfkbU was determined as shown in Fig.…”

Section: The Mechanism Underlying the Promoting Effect Of Polyhydroxymentioning

confidence: 99%

Enhanced ascomycin production in Streptomyces hygroscopicus var. ascomyceticus by employing polyhydroxybutyrate as an intracellular carbon reservoir and optimizing carbon addition

et al. 2021

Background Ascomycin is a multifunctional antibiotic produced by Streptomyces hygroscopicus var. ascomyceticus. As a secondary metabolite, the production of ascomycin is often limited by the shortage of precursors during the late fermentation phase. Polyhydroxybutyrate is an intracellular polymer accumulated by prokaryotic microorganisms. Developing polyhydroxybutyrate as an intracellular carbon reservoir for precursor synthesis is of great significance to improve the yield of ascomycin. Results The fermentation characteristics of the parent strain S. hygroscopicus var. ascomyceticus FS35 showed that the accumulation and decomposition of polyhydroxybutyrate was respectively correlated with cell growth and ascomycin production. The co-overexpression of the exogenous polyhydroxybutyrate synthesis gene phaC and native polyhydroxybutyrate decomposition gene fkbU increased both the biomass and ascomycin yield. Comparative transcriptional analysis showed that the storage of polyhydroxybutyrate during the exponential phase accelerated biosynthesis processes by stimulating the utilization of carbon sources, while the decomposition of polyhydroxybutyrate during the stationary phase increased the biosynthesis of ascomycin precursors by enhancing the metabolic flux through primary pathways. The comparative analysis of cofactor concentrations confirmed that the biosynthesis of polyhydroxybutyrate depended on the supply of NADH. At low sugar concentrations found in the late exponential phase, the optimization of carbon source addition further strengthened the polyhydroxybutyrate metabolism by increasing the total concentration of cofactors. Finally, in the fermentation medium with 22 g/L starch and 52 g/L dextrin, the ascomycin yield of the co-overexpression strain was increased to 626.30 mg/L, which was 2.11-fold higher than that of the parent strain in the initial medium (296.29 mg/L). Conclusions Here we report for the first time that polyhydroxybutyrate metabolism is beneficial for cell growth and ascomycin production by acting as an intracellular carbon reservoir, stored as polymers when carbon sources are abundant and depolymerized into monomers for the biosynthesis of precursors when carbon sources are insufficient. The successful application of polyhydroxybutyrate in increasing the output of ascomycin provides a new strategy for improving the yields of other secondary metabolites.

Biotech and App Biochem

Genus Streptomyces: Recent advances for biotechnological purposes

Júnior

Sousa²,

Oliveira

et al. 2023

Actinomycetes are a distinct group of filamentous bacteria. The Streptomyces genus within this group has been extensively studied over the years, with substantial contributions to society and science. This genus is known for its antimicrobial production, as well as antitumor, biopesticide, and immunomodulatory properties. Therefore, the extraordinary plasticity of the Streptomyces genus has inspired new research techniques. The newest way of exploring Streptomyces has comprised the discovery of new natural metabolites and the application of emerging tools such as CRISPR technology in drug discovery. In this narrative review, we explore relevant published literature concerning the ongoing novelties of the Streptomyces genus.