Table 2.

Health benefits and characteristics of the main postbiotic components.

Postbiotic	Main description	Health benefits in the host	Reference
Biosurfactants	Molecules synthesized during the late log or early stationary phase of the growth cycle. Amphiphilic molecules that are composed of glycolipids, lipopeptides, phospholipids, neutral lipids, polysaccharide-protein complexes, and free fatty acids	Disruption and prevention of biofilm formation by pathogenic microorganisms. Wetting, foaming, and emulsification properties, which help the pathogen to adhere, establish itself, and subsequently communicate in biofilms	Nataraj et al., 2020
Exopolysaccharides	Extracellular biopolymers synthesized or secreted by microorganisms during the exponential phase. Based on their monosaccharide composition, exopolysaccharides are further classified into homopolysaccharides and heteropolysaccharides	Biofunctional attributes such as antioxidant, cholesterol-lowering, immunomodulatory, and anti-aging effects; gut microbiota modulation; and anti-toxic, anti-biofilm, and antitumoral effects in preclinical trials	Lynch et al., 2018 and Nataraj et al., 2020
Short-chain fatty acids	Fatty acids with fewer than six carbon atoms in their chains. The most common are acetate, propionate, formate, and butyrate. LAB synthesize SCFAs from non-digestible carbohydrates. Also, bifidobacteria can synthesize short-chain fatty acids, for example acetate and formate	Management of inflammatory bowel disease and colorectal cancer due to their potentiality to overcome the inflammation and proliferation of cancerous cells	Gill et al. (2018) and Nataraj et al. (2020)
Teichoic acids	These are anionic glycopolymers that play key roles in determining the cell shape, regulation of cell division, and other fundamental metabolic aspects of cell physiology. Teichoic acids are generally of two kinds: lipoteichoic acids and wall teichoic acids	Antibiofilm actions against oral and enteric pathogens, immunomodulatory potential, and decreased leaky gut and inflammation	Barros et al., 2020 and Nataraj et al., 2020
Bacteriocins	LAB produce an array of extracellular antimicrobials that inhibit both pathogenic and spoilage-causing microorganisms	Inhibitory potential against various urogenital and antibiotic-resistant pathogens	Bartkiene et al., 2020 and Nataraj et al., 2020
Cell-free supernatant	Cell-free supernatant of LAB is a consortium of low-molecular-weight (hydrogen peroxide, organic acids, carbon dioxide, and di-acetylene) and high-molecular-weight (bacteriocins) compounds	Bioliquid-detergent that reduces the adhesion and biofilm formation of pathogens to various surfaces	de Almada et al., 2016 and Nataraj et al., 2020
Peptidoglycan	Peptidoglycan is a linear glycan strand cross-linked by peptides. The strands are constructed by bonding N-acetylglucosamine and N-acetylmuramic acid	Immunomodulatory, anti-proliferative, and anti-tumor effects	Nataraj et al., 2020
Cell-surface proteins	Proteins that are found in the plasma membrane or in the cell wall. They can be classified into four categories: proteins anchored to the cytoplasmic membrane, lipoproteins, proteins containing a C-terminal motif, and non-covalently bound proteins associated with the cell wall	Immunomodulatory action, secretion of antibacterial peptides, anti-inflammatory effects, anti-adhesion effects, strengthening of epithelial barrier properties, and biosorption of toxic heavy metals	Shigwedha et al., 2014 and Nataraj et al., 2020