Characterization and Optimization of Streptomyces albidoflavus MD102 as a heterologous expression chassis

Abstract

We report the isolation and characterization of Streptomyces albidoflavus MD102, a strain that can be used as a microbial chassis for the heterologous production of secondary metabolites. This strain, closely related to the widely used S. albidoflavus J1074, exhibits a compact genome, exceptional genetic tractability, rapid growth, and susceptibility to antibiotics. Whole-genome sequencing revealed the metabolic capabilities of S. albidoflavus MD102, highlighting its versatility in supporting the production of diverse secondary metabolites. Employing CRISPR/Cas9-assisted genome editing tools, we created mutant strains with reduced genome and cleaner chromatographic background. In addition to the deletion of several biosynthetic gene clusters (BGC), we inserted the global regulator bldA gene and geranyl diphosphate synthase (gpps) genes and an additional {Phi}BT1-attB attachment site into the chromosome to enhance the strains capability in producing secondary metabolites. S. albidoflavus MD102 will be a new addition to the repertoire of existing Streptomyces chassis, contributing to the advancement of secondary metabolite discovery and synthetic microbiology. IMPORTANCEThe pursuit of a universal Streptomyces microbial chassis for the heterologous production of secondary metabolites has proven elusive, prompting a more pragmatic approach to develop a suite of Streptomyces chassis. The current study introduces Streptomyces albidoflavus MD102 as a promising heterologous chassis with rapid growth, susceptibility to common antibiotics, and genetic tractability. Its close phylogenetic relation with the widely used versatile S. albidoflavus J1074 chassis and the traits gained from strain improvement place the engineered S. albidoflavus MD102 strains as useful chassis for the heterologous production of microbial secondary metabolites. A notable feature of S. albidoflavus MD102 that distinguishes it from J1074 and other Streptomyces chassis is the presence of metabolic genes in its genome putatively responsible for the degradation of aromatic compounds. This characteristic may endow the strain with the capability to convert petrogenic polycyclic aromatic hydrocarbons (PAHs) and substituted aromatics into valuable secondary metabolites.