Natural polysaccharides-based postbiotics and their potential applications

Abstract

Postbiotics, representing the newest member of the family of biotics, are metabolites produced as a result of fermentation of lactic acid bacteria (LAB) in the De Man, Rogosa, and Sharpe (MRS) medium which includes proteins, sugars and minerals. The components of postbiotics includes exopolysaccharides (EPS), short-chain fatty acids (SCFAs), bacteriocins, antioxidants, and metabolizing enzymes. Several studies indicate that postbiotics have multiple properties such as antimicrobial, immunomodulatory, antioxidant, anti-inflammatory, anti-obesity, anti-diabetic, and anti-tumoral properties. Natural polysaccharides refer to the polysaccharides obtained from biological organisms including algae, plants, animals, and microorganisms. Polysaccharides are either branched or linear macromolecules and are composed of a few major and some minor monosaccharides, including glucose, fructose, mannose, arabinose, galactose, fucose, galacturonic acid, glucosamine, galactosamine or their derivatives. Similar to postbiotics, polysaccharides also exhibit anti-inflammatory, antibacterial, antitumor, antiviral, immunomodulatory, and antioxidant properties. Although polysaccharides cannot be directly digested by the human body due to the lack of specific enzymes, they can be digested by gut-residing bacteria including but not limited to LAB. Recent studies indicate that large non-starch polysaccharides such as alginate, fucoidan, chitosan, carrageenan, and guar gum can be degraded into low molecular weight oligosaccharides which in turn can provide health benefits to the human health. These new findings inspired us to propose a polysaccharides-based postbiotics, also called glycanbiotics, and their potential applications. We propose that polysaccharides can be fermented by probiotics, and subsequent removal of bacteria will increase the safety of their produced metabolites, including oligosaccharides, disaccharides, monosaccharides and their derivatives. These polysaccharides-based postbiotics may mimic metabolization of polysaccharides in vitro and consequently broaden the applications of postbiotics. Non-probiotics such as Akkermansia muciniphila and other bacteria can also be used for glycanbiotics production, thus providing novel applications for human health.