The dual role of teichoic acids in gram-positive bacteria: Structural diversity dictates pathogenic and probiotic...

Teichoic acids (TAs) are fundamental anionic polymers in Gram-positive bacterial cell walls. Beyond structural roles, they act as crucial immunomodulators, with function dictated by structural diversity. This review elucidates how fine chemical structures, including the polyol backbone, D-alanylation, and glycosylation, form a molecular code governing their dualistic host interactions. Also, this work systematically compares wall teichoic acid and lipoteichoic acid from pathogens and probiotics. Pathogenic TAs often promote virulence by engaging TLR-2 and triggering pro-inflammatory responses. Conversely, probiotic TAs enhance epithelial barrier integrity, induce anti-inflammatory cytokines, and promote repair. The review further explores TAs roles in microbiome ecology via competitive exclusion and signaling, highlighting the translational potential of probiotic TAs as postbiotics. Furthermore, synthetic biology approaches for redesigning TAs synthesis, anticipating next-generation probiotics and novel anti-infective strategies are discussed. Deciphering this structural code is crucial for developing innovative functional foods and precision nutrition strategies.