AUTHOR=Lü Jin , Long Qingshan , Zhao Zhilong , Chen Lu , He Weijun , Hong Jiali , Liu Kai , Wang Yemin , Pang Xiuhua , Deng Zixin , Tao Meifeng 

TITLE=Engineering the Erythromycin-Producing Strain Saccharopolyspora erythraea HOE107 for the Heterologous Production of Polyketide Antibiotics

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.593217

DOI=10.3389/fmicb.2020.593217

ISSN=1664-302X

ABSTRACT=<p>Bacteria of the genus <italic>Saccharopolyspora</italic> produce important polyketide antibiotics, including erythromycin A (<italic>Sac. erythraea</italic>) and spinosad (<italic>Sac. spinosa</italic>). We herein report the development of an industrial erythromycin-producing strain, <italic>Sac</italic>. <italic>erythraea</italic> HOE107, into a host for the heterologous expression of polyketide biosynthetic gene clusters (BGCs) from other <italic>Saccharopolyspora</italic> species and related actinomycetes. To facilitate the integration of natural product BGCs and auxiliary genes beneficial for the production of natural products, the erythromycin polyketide synthase (<italic>ery</italic>) genes were replaced with two bacterial <italic>attB</italic> genomic integration sites associated with bacteriophages ϕC31 and ϕBT1. We also established a highly efficient conjugation protocol for the introduction of large bacterial artificial chromosome (BAC) clones into <italic>Sac. erythraea</italic> strains. Based on this optimized protocol, an arrayed BAC library was effectively transferred into <italic>Sac. erythraea</italic>. The large spinosad gene cluster from <italic>Sac. spinosa</italic> and the actinorhodin gene cluster from <italic>Streptomyces coelicolor</italic> were successfully expressed in the <italic>ery</italic> deletion mutant. Deletion of the endogenous giant polyketide synthase genes <italic>pkeA1</italic>-<italic>pkeA4</italic>, the product of which is not known, and the flaviolin gene cluster (<italic>rpp</italic>) from the bacterium increased the heterologous production of spinosad and actinorhodin. Furthermore, integration of pJTU6728 carrying additional beneficial genes dramatically improved the yield of actinorhodin in the engineered <italic>Sac. erythraea</italic> strains. Our study demonstrated that the engineered <italic>Sac. erythraea</italic> strains SLQ185, LJ161, and LJ162 are good hosts for the expression of heterologous antibiotics and should aid in expression-based genome-mining approaches for the discovery of new and cryptic antibiotics from <italic>Streptomyces</italic> and rare actinomycetes.</p>