Identification of bafilomycins and heterologous expression of its biosynthetic gene cluster from the Pearl River Estuary sediment-derived Streptomyces sp. SCSIO 40020

Abstract:

[Objective] To identify the macrolide antibiotic bafilomycins from the strain SCSIO 40020 isolated from the Pearl River Estuary sediment. To clone and heterologously express the biosynthetic gene cluster (BGC) of bafilomycins.[Methods] The strain SCSIO 40020 was identified based on phylogenetic analysis of its 16S rRNA gene sequence. The generated compounds from SCSIO 40020 were purified via normal phase-column chromatography and semi-preparative chromatography. The chemical structures of the isolated compounds were subsequently elucidated by comprehensive spectroscopic analyses. The bafilomycins BGC was identified by using bioinformatics approach. Through screening the bacterial artificial chromosome (BAC) library of this strain, the BAC containing the bafilomycins BGC was introduced into three Streptomyces hosts by conjugation for expression. Afterwards, the fermentation culture of the recombinant strains were analyzed on high-performance liquid chromatography (HPLC). [Results] The strain SCSIO 40020 was identified as Streptomyces genus and two macrolide compounds bafilomycins A₁and D were isolated from the fermentation crude extract. The bafilomycins BGC was cloned and successfully expressed in three heterologous Streptomyces hosts. In addition, the biosynthetic pathway of bafilomycins was proposed. [Conclusion] The bafilomycin-producing strain Streptomyces sp. SCSIO 40020 was obtained from the Pearl River Estuary. The BAC heterologous expression system of this strain was successfully established. Moreover, the bafilomycins BGC was successfully expressed in Streptomyces lividans SBT18, Streptomyces coelicolor M1154 and Streptomyces albus J1074 for the first time, which laid solid foundation for the production of bafilomycin analogues and mining other interesting BGCs from Streptomyces sp. SCSIO 40020 in the further study.