“…Studies have shown that benefits for human health are attributed to consumption of probiotics, mainly for GIT diseases ( Fedorak et al, 2015 ; Acurcio et al, 2017 ), though also for other diseases, including osteoporosis ( Collins et al, 2018 ), cancer ( Zaharuddin et al, 2019 ), obesity and type 2 diabetes ( Saez-Lara et al, 2015 ; Wang et al, 2017 ; Hsieh et al, 2018 ), depression ( Wallace et al, 2020 ), and atopic dermatitis ( Rather et al, 2016 ). In this context, the main mechanisms of action described for these microorganisms in the host include: (i) colonization and regulation of a dysbiotic intestinal microbiota ( Shi et al, 2017 ); (ii) protection of the epithelial barrier by maintaining tight junction integrity ( Blackwood et al, 2017 ); (iii) induction of mucin production ( Aliakbarpour et al, 2012 ) and B-cell-secreting IgA, which are important defense mechanisms necessary to maintain epithelial integrity and to protect the intestine from the external environment; (iv) increasing adherence to the intestinal mucosa and inhibiting of concomitant pathogen adherence based on competition for available nutrients and sites of mucosal adhesion ( Collado et al, 2010 ; Monteagudo-Mera et al, 2019 ); (v) competitive exclusion of pathogenic microorganisms, such as Staphylococcus aureus and Salmonella typhimurium ( Halder et al, 2017 ; Plaza-Díaz et al, 2017 ); (vi) production of antimicrobial substances such as acetic and lactic acids, and bacteriocins, which have strong inhibitory effects against Gram-negative bacteria and have been considered as the main antimicrobial compounds produced by probiotics against pathogens ( Alakomi et al, 2000 ; De Keersmaecker et al, 2006 ; Makras et al, 2006 ; Bermudez-Brito et al, 2012 ; Mokoena, 2017 ; Gaspar et al, 2018 ; Castilho et al, 2019 ); (vii) production and secretion of metabolites of SCFAs with anti-inflammatory properties, such as acetate, propionate, and butyrate, which exert beneficial effects on intestinal and immune cells, being important compounds for cell proliferation, cell differentiation, and gene expression, and they are signaling molecules of immunological pathways; butyrate is the primary energy source of colonocytes, and it has an epithelial barrier function; SCFAs can also induce expression of the anti-inflammatory cytokine IL-10, inhibiting inflammatory responses ( Parada Venegas et al, 2019 ); (viii) inhibition of the activation of the NF-κB signaling pathway ( Kaci et al, 2011 ; Gao et al, 2015 ); (ix) interaction with the gut–brain axis via the production of metabolites such as γ-aminobutyric acid (GABA) ( Kim N. et al, 2018 ); and (x) modulation of the host’s innate and/or adaptive immune system responses through interaction with epithelial cells, ...…”