## 4 Bioactive Metabolites
### Carbohydrates: Polysaccharides (EPS and IPS) and Oligosaccharides
producing IPS (4.8 g/L) and EPS (3.94 g/L) [28]. [PERSON] et al. report that adding OMW to the liquid substrate of _G. resinaceum_ resulted in increasedquantities of IPS (5.2 g/L) [92]. Many studies seek to optimize EPS production in liquid cultures by deploying a multitude of carbon and nitrogen sources, different light intensities, and wavelengths [94]. Homogenization of the mycelium inoculant by sonoporation proved to be effective in increasing EPS production and reducing the required quantity of starter mycelium in submerged cultures of _G.__Incidum_[95]. It is important to mention that the production of EPS by fungi in liquid cultures is negatively correlated with IPS, indicating that the amount synthesized significantly decreases after the 8 th or 12 th day of culture [96]. IPS in liquid cultures of _V. volvocae_ were also found to start decreasing after the 8 th day and continued to decrease until the end of the culture. IPS were produced in greater quantities when the substrate C/N ratio was 40 [22]. Beta-glucans are the most common polysaccharides found in the cell walls of Ascomycata and Basidiomycota [97]. Beta-glucans are groups of polysaccharides or dietary fibers composed of D-glycose monomers, linked by \(\beta\) (1\(\rightarrow\)3) and \(\beta\) (1\(\rightarrow\)6) glycosidic bonds [98]. Beta-glucans are classified as dietary fibers and prebiotics because they cannot be hydrolyzed by the gastric enzymes of mammals and reach the large intestine undigested, where they are fermented by the gut microbiota with potential health benefits for the host [99]. Beta-glucans cannot be synthesized by the human body, which leads to their recognition by the immune system, inducing both adaptive and innate immune responses. Current research has established that beta-(1\(\rightarrow\)3,1\(\rightarrow\)6)-D-glucans are efficient immunostimulant agents that can trigger a variety of molecular interactions that are not yet clearly understood [100]. It has been established that \(\beta\)-glucans can play a role in the prevention of insulin resistance, dyslipidemia, hypertension, and obesity [101]. A recent systematic literature review of 34 clinical trials performed using fungal \(\beta\)-glucans summarized the main physiological impacts on patients as follows: a strengthened immune defense that reduces the incidence and symptoms of respiratory infections, improvement of allergic symptoms, improvement of mood states, and improvement of overall wellbeing. No adverse effects related to the supplementation of \(\beta\)-glucans were noted [102]. The content of fungi in beta-glucans varies from 16% to 53% and is influenced by factors such as species, strain, cultivation conditions, and total dietary fiber content. Several studies have studied the in vitro antibacterial and antiviral activity of beta-glucans through the activation of the nonspecific immune system [103]. Beta-(1,3-1,6) glucans also exhibit a radioprotective effect, which has been investigated in vivo with mice [104] and has also been successfully used as a radioprotectant to treat and prevent radiation and chemotherapy-related injuries [105]. _P.__ostreatus_ fruiting bodies cultivated in agricultural residues contained high quantities of \(\beta\)-glucans (28.28% to 48.42% dw) [106]. Another study reports that the use of olive mill wastes in the substrate of _G.__Incidum_ resulted in up to a 43% increase in the \(\beta\)-glucan content of the produced mushrooms [107]. An extensive review of the mechanisms by which polysaccharides help the treatment of type 2 diabetes enumerates multiple compounds isolated from macrofungi [65]. Namely, submerged cultivation of _Laetiporus sulphureus_ and _G.__Incidum_ produced polysaccharides with antidiabetic action in rats. A glucan-rich polysaccharide isolated from _Pleurotus sajor-caju_ alleviated hyperglycemia and hyperinsulinemia in diabetic mice.