Optimization of Triterpenoid Production in Floccularia luteovirens Liquid Culture Using Response Surface Methodology

The rare edible and medicinal mushroom Floccularia luteovirens faces challenges from limited wild resources and low triterpenoid yield in submerged fermentation. To address this, we systematically optimized the fermentation medium using one-factor-at-a-time experiments combined with Response Surface Methodology (RSM). Wheat flour, peptone, and KH2PO4 were identified as the optimal carbon, nitrogen, and inorganic salt sources, respectively. Subsequently, we developed and validated distinct, highly predictive mathematical models for intracellular (R2 = 0.9989) and extracellular (R2 = 0.9984) triterpenoid production. This yielded two optimized media: one designed to maximize intracellular accumulation (29.71 g/L wheat flour, 2.03 g/L peptone, 1.02 g/L KH2PO4), achieving a yield of 18.83 mg/g, and another tailored for high extracellular secretion (30.28 g/L wheat flour, 2.08 g/L peptone, 1.05 g/L KH2PO4), achieving a titer of 0.63 g/L. The experimental results for both targets closely matched the model predictions. Thus, this study not only significantly enhanced overall triterpenoid production but also delineated nutrient-specific strategies for targeting different product locales. The findings provide a reliable technical and theoretical foundation for the scalable and sustainable production of these bioactive compounds.