Essential roles of ellagic acid-to-urolithin converting bacteria in human health and health food industry: An updated review

Abstract

BackgroundUrolithins, including urolithin A (Uro-A), are metabolites of ellagitannins (ETs) and ellagic acid (EA) produced by gut bacterial metabolism and exhibit multifarious health-promoting bioactivities. As the capacity to produce urolithins varies widely among individuals, identifying urolithin-producing bacteria and elucidating the metabolic pathways from EA to Uro-A have garnered intense research attention worldwide. Scope and approachThis review discusses the latest advancements in the identification of bacterial strains capable of converting EA into Uro-A, and the development of functional foods enriched in Uro-A. Topics covered include the approaches for screening of urolithin-producing bacteria, optimization of fermentation processes, analysis of metabolic pathways, and the employment of gene editing and synthetic biology techniques. Moreover, the development and industrialization of Uro-A-enriched functional foods, and the discovery of next-generation probiotics are also explored. Key findings and conclusionsBacteria capable of producing Uro-A can be employed for producing fermented functional foods. As the novel multi-subunit molybdoenzyme is only present in specific gut bacteria, for example Lachnospiraceae spp., for converting Uro-C to Uro-A, gene editing and synthetic biology techniques can be applied to substantially enhance the efficiency of Uro-A production. On top of this, this review also sheds light on a few future research directions, including strategies to improve the yield and consistency of Uro-A production, and expansion of its applications in health-related industries.