Overcoming cultivation challenges in Tuber borchii via grain-based solid-state fermentation with plant somatic embryo...

The long maturation period and strong environmental reliance of Tuber borchii's fruiting bodies limit its commercial and medicinal utilization, leading to unstable yield and limited supply of bioactive compounds. Developing a controlled cultivation strategy for consistent production of truffle-derived metabolites, therefore, remains a critical challenge. In this study, grain-based solid-state fermentation was investigated as an alternative platform for mycelial biomass generation and triterpenoid production under controlled conditions. During the main solid-state cultivation phase, adlay was identified as the most effective substrate, yielding the highest biomass (45.32 ± 1.58 mg/g substrate) and triterpenoid content (1.00 ± 0.13 mg/g substrate) on day 28. Optimization of fermentation parameters was conducted by evaluating initial pH, moisture content, and inoculum age. The optimal conditions were found to be pH 7, 50% moisture content, and an inoculum age of 21 days, balancing both mycelial growth and triterpenoid accumulation. Regarding nutrient supplementation, 3% (w/v) glucose was identified as the most effective carbon source, resulting in the highest biomass and triterpenoid yield per gram of substrate (1.37 ± 0.20 mg/g substrate), while 1% (w/v) yeast extract proved to be the most effective nitrogen source, yielding 88.42 ± 1.77 mg/g substrate mycelial biomass and 1.91 ± 0.12 mg/g substrate triterpenoid content. Furthermore, co-culturing with 1 g Quercus glauca somatic embryos increased the mycelial biomass and triterpenoid content to 100.72 ± 1.98 mg/g substrate and 2.39 ± 0.14 mg/g substrate, respectively. Overall, the study demonstrated the potential of solid-state fermentation as a sustainable method for the production of T. borchii mycelia and triterpenoids under controlled conditions.