Exploiting endophytic microbes as micro-factories for plant secondary metabolite production

Plant secondary metabolites have significant potential applications in a wide range of pharmaceutical, food, and cosmetic industries by providing new chemistries and compounds. However, direct isolation of such compounds from plants has resulted in over-harvesting and loss of biodiversity, currently threatening several medicinal plant species to extinction. With the breakthrough report of taxol production by an endophytic fungus of Taxus brevifolia, a new era in natural product research was established. Since then, the ability of endophytic microbes to produce metabolites similar to those produced by their host plants has been discovered. The plant "endosphere" represents a rich and unique biological niche inhabited by organisms capable of producing a range of desired compounds. In addition, plants growing in diverse habitats and adverse environmental conditions represent a valuable reservoir for obtaining rare microbes with potential applications. Despite being an attractive and sustainable approach for obtaining economically important metabolites, the industrial exploitation of microbial endophytes for the production and isolation of plant secondary metabolites remains in its infancy. The present review provides an updated overview of the prospects, challenges, and possible solutions for using microbial endophytes as micro-factories for obtaining commercially important plant metabolites.