“…Heterologous expression can often aid in the production of adequate levels of compound for evaluation, particularly when expression hosts are derived from industrial production strains or highly engineered laboratory strains [9, 11, 34, 40]. Synthetic biology approaches are also being developed which focus on refactoring secondary metabolic gene clusters, either in producing hosts via genetic recombination, or in ‘clean’ heterologous hosts via gene synthesis [22, 62]. Heterologous expression approaches have many advantages in that they are not limited to gene clusters derived from cultivatable microbes, that the products of heterologous expression can be identified by comparatively straightforward differential metabolomic analysis of the clean and transformed host, and that heterologous systems, once established, can be readily genetically manipulated to diversify the encoded natural products.…”