LED Light Spectra Modulate Growth, Morphogenesis, and Bioactive Compound Production in Cordyceps militaris (Ascomycota)

Light is a crucial environmental factor influencing fungal development and secondary metabolite biosynthesis. In this study, we investigated the effects of nine different LED light spectra on the growth, morphogenesis, and production of bioactive compounds in <i>Cordyceps militaris</i> strain DT22. Mycelial cultures and stromata were cultivated under controlled LED conditions, and their morphological characteristics, carotenoid, adenosine, and cordycepin contents were evaluated. Additionally, the expression levels of genes related to stromata development (<i>CmHYD1</i>), carotenoid biosynthesis (<i>CmFHP</i>), and cordycepin biosynthesis (<i>CmCNS3</i>) were analyzed by qRT-PCR. The results demonstrated that LED light treatments significantly influenced mycelial color, colony diameter, stromata formation, and biomass accumulation. Particularly, light formulas RW23 (2 Red:3 White) and wW (Warm White) promoted larger colony diameters and higher fresh and dry weights of stromata. Total carotenoid content peaked at the orange mycelial stage under RB (5 Red:1 Blue) and nW (Neutral White) treatments, but declined during primordia and mature stages. Cordycepin accumulation was highest under RBW (3 Red:2 Blue:1 White) treatment, whereas adenosine content showed no significant variation across light conditions. Gene expression analysis revealed that <i>CmHYD1</i> and <i>CmFHP</i> were upregulated under most LED treatments, while <i>CmCNS3</i> exhibited variable expression patterns. The mating-type gene <i>MAT1.1.1</i> remained stable across treatments, whereas <i>MAT1.1.2</i> showed a notable decrease under certain spectral conditions. Overall, our findings highlight the potential of tailored LED light combinations to optimize stromata production and bioactive metabolite synthesis in <i>C. militaris</i>, offering insights into environmental modulation strategies for industrial-scale cultivation.