Medicinal Plant Research 2024, Vol.14, No.5, 297-307 http://hortherbpublisher.com/index.php/mpr 301 Organic and inorganic fertilizers can also play a role in improving substrate quality and yield. The use of wheat bran as a supplement in various substrates has been found to enhance mycelial growth and yield. For example, substrates supplemented with wheat bran have shown higher biological efficiency and yield compared to those without (Rashad et al., 2019; Thiribhuvanamala and Krishnamoorthy, 2021). 4.3 The impact of physical and chemical properties of substrates on yield The physical properties of the substrate, such as particle size and moisture content, also are crucial for the successful cultivation of G. lucidum. A suitable moisture content is associated with higher yield. For example, research has found that using a palm sawdust substrate with 67.36% humidity significantly increases the yield of G. lucidum. This moisture level provides an optimal growth environment, achieving a yield of 66.25 g/kg (Ohmayed et al., 2020). Additionally, substrates with smaller particle sizes, like sawdust, tend to support better mycelial colonization and fruiting body formation (Cortina-Escribano et al., 2020; Fedorov et al., 2022). Chemical properties such as pH value and nutrient content also significantly affect the yield of G. lucidum. Substrates with a pH value around 6.93 have been found to be optimal for mushroom growth (Ohmayed et al., 2020). Moreover, substrates with balanced electrical conductivity and salinity levels can enhance nutrient availability and support higher yields (Kuhar et al., 2018). 5 Impact of Cultivation Substrates on Quality Parameters 5.1 Active compound content The content of active compounds such as polysaccharides and triterpenoids in G. lucidum is significantly influenced by the type of cultivation substrate used. Ye et al. (2018) found that spraying salicylic acid and calcium ions during the fruiting body development stage of G. lucidum can significantly enhance its triterpenoid and polysaccharide content. The results showed that using salicylic acid alone increased triterpenoid content by 23.32%, while combining it with calcium ions increased polysaccharide and triterpenoid contents by 9.02% and 13.61%, respectively. Gene expression analysis indicated that these treatments affected the transcription levels of relevant genes, with particularly significant upregulation observed in triterpenoid biosynthesis genes. Another study found that salicylic acid stimulates the biosynthesis of secondary metabolites not only by directly promoting triterpenoid synthesis but also by increasing the generation of mitochondrial reactive oxygen species (ROS). Salicylic acid can inhibit the activity of mitochondrial complex III, leading to elevated ROS levels, which in turn regulate triterpenoid synthesis (Liu et al., 2018). A substrate formulation with added olive oil and copper has also been found to affect the bioactive chemical composition of G. lucidum, including total triterpenoids and high-molecular-weight carbohydrates (Bidegain et al., 2019). Additionally, olive by-products used as a cultivation medium for G. lucidumnot only enhance the content of bioactive components, such as α-glucans and β-glucans, but also increase protein content, indicating that olive residues contribute to improving the functional and prebiotic properties of G. lucidum(Koutrotsios et al., 2019). The optimization of media composition in solid-state fermentation using highland barley grains also demonstrated a significant increase in polysaccharide production, validating the importance of substrate composition in enhancing active compound content (Liu et al., 2020). 5.2 Physical properties The physical properties of G. lucidum, such as color, size, and texture, are also affected by the cultivation substrate. Studies have shown that the cultivation medium of G. lucidumsignificantly influences the surrounding microbial community and metabolic pathways at different growth stages. Microbial diversity is particularly high during the elongation stage, with changes in nitrogen, phosphorus, and potassium levels impacting the physical and chemical properties of the medium (Zhang et al., 2018). Bidegain et al. (2019) highlighted that the medium formulation for G. lucidum affects the activity of its chemical components, with the addition of various supplements leading to notable increases in triterpenoid and phenolic compound content, and different formulations resulting in variations in color and texture.
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