Increasing the heterologous production of spinosad in Streptomyces albus J1074 by regulating biosynthesis of its polyketide skeleton

Abstract

Spinosyns are natural broad-spectrum biological insecticides with a double glycosylated polyketide structure that are produced by aerobic fermentation of the actinomycete, Saccharopolyspora spinosa. However, their large-scale overproduction is hindered by poorly understood bottlenecks in optimizing the original strain, and poor adaptability of the heterologous strain to the production of spinosyn. In this study, we genetically engineered heterologous spinosyn-producer Streptomyces albus J1074 and optimized the fermentation to improve the production of spinosad (spinosyn A and spinosyn D) based on our previous work. We systematically investigated the result of overexpressing polyketide synthase genes ( spnA , B , C , D , E ) using a constitutive promoter on the spinosad titer in S. albus J1074. The supply of polyketide synthase precursors was then increased to further improve spinosad production. Finally, increasing or replacing the carbon source of the culture medium resulted in a final spinosad titer of ∼70 mg/L, which is the highest titer of spinosad achieved in heterologous Streptomyces species . This research provides useful strategies for efficient heterologous production of natural products.

Exploration of Streptomyces fradiae J1–021 as a Potential Host for the Heterologous Production of Spinosad

“…36 Peak spinosad titer was obtained in heterologous Streptomyces by adding or replacing the carbon source. 7 However, the original fermentation conditions limited the growth of overexpressing strains YD01 and YD02. Further optimization of the culture medium is necessary to identify the most suitable carbon, nitrogen sources, and inorganic salts.…”

“…6 Furthermore, spinosad production was increased to 70 mg/L by overexpressing the PKS genes, increasing the precursor supply, and optimizing carbon sources. 7 The expression of artificial spinosad BGC in S. albus J1074 yielded 1.11 mg/L spinosad. 8 However, scaling up spinosad production to industrial levels through heterologous expression remains challenging, owing to precursor deficiency or a dearth of mature fermentation strategies.…”

Streptomyces: The biofactory of secondary metabolites

“…A variety of cellulolytic and hydrolytic enzymes produced by Streptomyces may enter into the plant materials by rupturing the epidermal cell walls and middle lamellae between plant cells ( Viaene et al, 2016 ). Spinosad from actinomyces Saccharopolyspora spinosa was registered by the EPA as a new chemical class of insecticides with a double glycosylated polyketide structure, and it was now accumulated heterologously at the highest yield (70 mg/L) in Streptomyces albus , while in Streptomyces hosts, pathway refactoring led to the production of some novel spinosad derivatives ( Song et al, 2020 ; An et al, 2021 ).…”

A non-carboxylative route for the efficient synthesis of central metabolite malonyl-CoA and its derived products

“…Besides E. coli and S. gilvosporeus, we continued to assess the applicability of NCM pathway in other type of cells for synthesis of other types of MDPs. Saccharopolyspora spinosa is a Gram-positive, nonmotile, lamentous bacteria, as well as the native producer for spinosad (a mixture of spinosyns A and D), which represents a broad-spectrum macrolide insecticide 54 . Production of spinosad is initiated by a PKS I which uses 9 molecules of malonyl-CoA, 1 molecule of propionyl-CoA and 1 molecule of methylmalonyl-CoA as substrates (Fig.…”