Heterologous expression facilitates the discovery and characterization of marine microbial natural products

Microbial natural products and their derivatives have been developed as a considerable part of clinical drugs and agricultural chemicals. Marine microbial natural products exhibit diverse chemical structures and bioactivities with substantial potential for the development of novel pharmaceuticals. However, discovering compounds with new skeletons from marine microbes remains challenging. In recent decades, multiple approaches have been developed to discover novel marine microbial natural products, among which heterologous expression has proven to be an effective method. Facilitated by large DNA cloning and comparative metabolomic technologies, a few novel bioactive natural products from marine microorganisms have been identified by the expression of their biosynthetic gene clusters (BGCs) in heterologous hosts. Heterologous expression is advantageous for characterizing gene functions and elucidating the biosynthetic mechanisms of natural products. This review provides an overview of recent progress in heterologous expression-guided discovery, biosynthetic mechanism elucidation, and yield optimization of natural products from marine microorganisms and discusses the future directions of the heterologous expression strategy in facilitating novel natural product exploitation.