Pelletized Growth in Cordyceps militaris Is Associated with Coordinated Cell Wall Remodeling and Stress Defense

Morphological control in submerged fermentation is a well-established method for enhancing bioactive metabolite production in filamentous fungi. However, the molecular mechanisms linking morphology to fermentation efficiency remain insufficiently understood. In this study, supplementing 1.5% Tween 80 (P80) at the seed culture stage of Cordyceps militaris consistently induced the formation of compact, uniform mycelial pellets. This morphological induction at the seed stage enhanced fermentation performance, increasing exopolysaccharide (EPS) titer by 71.1% and reducing the production cycle by 24 h. Transcriptomic analysis revealed that pelletized cultures exhibited transcriptional patterns associated with MAPK signaling related to cell wall integrity and upregulation of genes involved in cell wall remodeling. Additionally, pelletized cultures displayed a reduced oxidative burden and were associated with enhanced antioxidant capacity. These findings link morphology induction to cell wall remodeling and oxidative stress defense, offering a potentially scalable strategy for industrial polysaccharide production in medicinal fungi.