Immunomodulatory Characteristics of Probiotics: Mechanisms, Applications, Challenges, and Future Perspectives

Fermented functional food products are one of the key segments of food processing industry. fermentation helps to improve organoleptic properties of food, increases shelf life and produces health beneficial bioactivecompounds. Traditionally, the fermented micronutrients have been considered the main substrate but recent study clarifies that secondary metabolites like polyphenols are emerging to ferment effectively as a substrate. However, polyphenol have long been known as antimicrobial agents, but growing scientific evidences shows that they exert selective effect on bacterial communities whereas they suppress the growth of pathogenic microorganisms, but they promotes the growth, survival and metabolic activity of probiotic bacteria such as Lactobacillus rhamnosus GG. In contrast, probiotic bacteria not only remain alive in polyphenol rich plant or vegetable extracts, rather they starts the probiotification based fermentation, that improves the bioavailability, produces new bioactive metabolites, enhancement of total polyphenol content as well as immunomodulatory and functional properties are significantly increased. Furthermore, selective probiotic fermentation or probiotic fortification of polyphenol-rich plant and vegetable extracts paves the way for the development of new functional foods and bioactive formulations for pharmaceutical, food, and agricultural applications. This narrative review specifically focuses on the potential for enhancing the immunomodulatory and functional potential of plant/vegetable extracts through Lactobacillus or lactic acid bacteria based probiotification, and highlights the emerging bidirectional relationship between probiotic bacteria and polyphenols.