## 4 Bioactive Metabolites
### Carbohydrates: Polysaccharides (EPS and IPS) and Oligosaccharides  
Polysaccharides are the most abundant carbohydrates found in nature; they are crucial for life maintenance in a variety of organisms such as plants, animals, microorganisms, and seaweeds. Polysaccharides are long-chain biopolymers composed of more than 10 monosaccharide units connected by glycosidic bonds, whereas oligosaccharides contain 3 to 10 monosaccharides [81]. Polysaccharides exhibit a wide variety of structures composed of different monosaccharides, glycosidic bonds, and functional groups. The precise chemical structure of polysaccharides can be investigated with a combination of analytical methods such as FTIR, NMR < Raman spectroscopy, GC, GC-MS, and HPLC. Their most common components are pyranoses such as glycose, galactose, mannose, xylose, and arabinse [82]. The diversity of their constituent monosaccharide composition and structure is responsible for their different biological activities. There is a close relationship between the polysaccharide's structure and biological activity [83]. The different chemical structures and chain conformations are also responsible for the different activities of polysaccharides [84]. They play an important role in functions such as cell recognition, growth and differentiation, metabolism, embryonic development, immune response, energy storage, structural support, and antigenicity [85]. Polysaccharides found in fungi are made up of glucans, which are made of D-glycose monomers, two glucose units linked by \(\alpha\)-glycosidic or \(\beta\)-glycosidic bonds. They all contain a \(\beta\)-linked glycose backbone, but the pattern and degree of branching vary from species to species. The \(\alpha\) or \(\beta\) linkages can form heteroglycans such as mannose, galactose, arabinse, fucose, and xylose. Polysaccharides can also bind to proteins, protein residues, and peptides to create polysaccharide-protein complexes or peptide complex groups [86]. Microbial polysaccharides are categorized into intra-cellular polysaccharides (IPS) and extra-cellular polysaccharides (EPS), depending on their location. Due to the polysaccharides not being encoded in the genome and their structural complexity, there is little information available regarding their biosynthesis [87]. There are data on polysaccharides produced from 651 species of fungi [88] to which there are multiple confirmed biological functions attributed, including antidiabetic, antioxidant, immunomodulatory, hepatotoxicity [89], antitumor, antiviral, anti-inflammatory, renal protective, and radioprotective actions [74], regulation of glycolipid metabolism and gut microbiota, anti-nephritic and antiangiogenic activity, and improvement of memory impairment [83]. Examples of mushroom polysaccharides isolated and characterized are pleuran from _Pleurotus_ species, lentinan from _L. edodes_, gangadern from _G. lucidum_, agartime from _Agaricus_ sp., grifolans from _G. fondose_, and calocyban from _Calocyhe indica_[61]. Polysaccharides are major structural cell wall components of mushrooms, but they can be produced excellularly in large amounts by the mycelium of macrofungi in liquid/submerged cultivation. This is not always the case, because the conditions required for their exo-cellular production are still under study [68]. Nevertheless, liquid cultivation of macrofungi mycel results in much faster production of polysaccharides in comparison to fruitbody production and is a promising tool for mass-scale industrial production [17]. It should be mentioned that optimum conditions for EPS production can vary greatly for fungi in the same genus [90] and even between strains of the same species [91]. Apart from species and strain, the most important growth conditions for optimal EPS production are: type of culture, oxygen supply, temperature, pH, carbon and nitrogen source, content and ratio, salt content, and cultivation length [25; 28; 92; 93]. [PERSON] et al. (2021) used molasses as a substrate in liquid cultures of _Morchella_ sp.