Strain improvement of Cordyceps militaris for optimized bioactive metabolite biosynthesis: current progress and prospective approaches.

Cordyceps militaris is a rare and highly valued medicinal fungus that has attracted considerable attention due to its production of diverse bioactive compounds, including nucleosides such as cordycepin, polysaccharides, lovastatin, carotenoids, etc., all of which exhibit significant nutritional and therapeutic potential. However, the large-scale utilization of C. militaris is constrained by several critical challenges. A major limitation is the progressive degeneration of strains over successive subcultures, which adversely affects fruiting body formation and metabolite biosynthesis. Moreover, genetic instability during long-term culture, contamination risks in large-scale production, and the lack of standardized cultivation and extraction protocols often result in variable product quality. The absence of efficient genetic transformation systems and the low success rate of genome editing approaches further complicate efforts in molecular strain improvement. This review provides a comprehensive overview of the principal bioactive compounds produced by C. militaris and critically evaluates the current challenges and limitations associated with both conventional and advanced strain improvement strategies. These include conventional approaches such as mutagenesis and protoplast fusion, as well as genome-editing technologies like CRISPR/Cas9, which are employed to enhance the biosynthesis of target metabolites. Moreover, the integration of metabolic engineering frameworks offers significant potential for rational strain design, optimization of bioprocesses, and the discovery of novel therapeutic agents.