Advances in the biosynthesis, diversification, and hyperproduction of ganoderic acids in Ganoderma lucidum

Ganoderic acids (GA) are one of the important secondary metabolites acquired from Ganoderma lucidum ( G. lucidum ) with a wide range of pharmacological activities and therapeutic effects on human ailments. They are triterpenes with four cyclic and two linear isoprenes and products of the mevalonate pathway. GA serve as a valuable resource for the development of new drugs; however, they are usually produced at very low concentrations and the producing mushroom requires tedious field cultivation for industrial application. Additionally, the magnitude of different types of GA isolated with different bioactivities reiterates the need to determine the basis of diversification. The elucidation of GA biosynthesis regulatory mechanisms has attained heightened interest from scientists and warranted the emergence of various strategies to control production as well as increase yield. In this review, we discuss important insights into the environmental and genetic regulation of GA biosynthesis. We explore viable avenues for GA hyper-production and challenges in elucidating the diversification of GA.