microbes isolated from dental plaque of healthy human donors Raw sequence reads. Streptococcus vestibularis, Gemella haemolysans, Streptococcus gwangjuense

The oral cavity, one of the primary interfaces for host-microbe interactions, features complex microbiota. The interaction between the oral microbiome with the host proteins often involves the recognition of microbial cell wall carbohydrates by the carbohydrate-binding proteins residing in the oral cavity, lectins being one of them. Zymogen granule protein 16 homolog B (ZG16B) is one such less explored human soluble lectins, expressed in high abundance in the serous and seromucous acinar cells of the submandibular and sublingual glands in the oral cavity. To elucidate the microbe-binding of ZG16B, we generated a microbial glycan analysis probe deploying recombinant lectin conjugated to fluorophore or biotin. We observed several bacterial isolates from the oral biofilms of four volunteers that were bound by mGAP based on Cy5-conjugated ZG16B. Whole genome shotgun sequencing of 14 representative isolates, including positive and negative binders of ZG16B mGAP, revealed that ZG16B predominantly binds to oral commensal Streptococcus vestibularis, whose genome sequences are closely related to strain NCTC12167. The second most abundant microbial target of ZG16B is distinct Gemella haemolysans strains related to the FDAARGOS 740 sequence. The isolates that do not bind to ZG16B are identified as Streptococcus oralis strains related to strain SF100. We also observed that ZG16B showed a bacteriostatic effect on Streptococcus vestibularis by aggregating the microbes, but not on other non-binding oral Streptococci. Therefore, by converting ZG16B into a functional mGAP, we successfully confirm the biological relevance of ZG16B in selective binding to the oral commensals and maintaining bacterial homeostasis in the oral cavity via lectin-mediated host-microbe interaction. A similar approach can be extended to other human soluble lectins to decipher their biological roles.