Microbial exopolysaccharides (EPSs) are receiving growing interest today, owing to their diversity in chemical structure and source, multiple functions, and immense potential applications in many food and non-food industries. Their health-promoting benefits for humans deserve particular attention because of their various biological activities and physiological functions. The aim of this paper is to provide a comprehensive review of microbial EPSs, covering (1) their chemical and biochemical diversity, including composition, biosynthesis, and bacterial sources belonging mainly to lactic acid bacteria (LAB) or probiotics; (2) their technological and analytical aspects, especially their production mode and characterization; (3) their biological and physiological aspects based on their activities and functions; and (4) their current and future uses in medical and pharmaceutical fields, particularly for their prebiotic, anticancer, and immunobiotic properties, as well as their applications in other industrial and agricultural sectors.

Antioxidants are often associated with a variety of anti-aging compounds that can ensure human and animal health longevity. Foods and diet supplements from animals and plants are the common exogenous sources of antioxidants. However, microbial-based products, including probiotics and their derivatives, have been recognized for their antioxidant properties through numerous studies and clinical trials. While the number of publications on probiotic antioxidant capacities and action mechanisms is expanding, that of synbiotics combining probiotics with prebiotics is still emerging. Here, the antioxidant metabolites and properties of synbiotics, their modes of action, and their different effects on human and animal health are reviewed and discussed. Synbiotics can generate almost unlimited possibilities of antioxidant compounds, which may have superior performance compared to those of their components through additive or complementary effects, and especially by synergistic actions. Either combined with antioxidant prebiotics or not, probiotics can convert these substrates to generate antioxidant compounds with superior activities. Such synbiotic-based new routes for supplying natural antioxidants appear relevant and promising in human and animal health prevention and treatment. A better understanding of various component interactions within synbiotics is key to generating a higher quality, quantity, and bioavailability of antioxidants from these biotic sources.

Probiotics are live microorganisms recognized as natural candidates to substitute antibiotic substances, usually used to treat bacterial infections responsible for numerous human and animal diseases. Antibiotics are mostly prescribed for treating infections caused by bacteria. However, their excessive and inappropriate use has resulted in the increase of bacterial antimicrobial resistance (AMR) and host microbiota imbalance or dysbiosis phenomena. Even though antibiotics are the most well-known lifesaving substances, the AMR within the bacterial community has become a growing threat to global health, with the potential to cause millions of deaths each year in the future. Faced with these worldwide issues, it is high time to discover and develop antibiotic alternatives. There exists some evidence of probiotic roles in antagonizing pathogens, modulating immune systems, and maintaining general host health by restoring the gut microbiota balance. The multi-antimicrobial action mechanisms of such beneficial living microorganisms are one approach to practicing the “prevention is better than cure” concept to avoid antibiotics. The current review proposes a comprehensive description of antibiotic-related AMR issues and the potential of probiotics as antibiotic alternatives, while discussing pros and cons, as well as some evidence of beneficial uses of probiotics for human and animal health protection through recent results of experimental models and clinical trials.