The gut microbe Akkermansia (A.) muciniphila becomes increasingly important as its prevalence is inversely correlated with different human metabolic disorders and diseases. This organism is a highly potent degrader of intestinal mucins and the hydrolyzed glycan compounds can then serve as carbon sources for the organism itself or other members of the gut microbiota via cross-feeding. Despite its importance for the hosts' health and microbiota composition, exact mucin degrading mechanisms are still mostly unclear. In this study, we identified and characterized three extracellular β-galactosidases (Amuc_0771, Amuc_0824, and Amuc_1666) from A. muciniphila ATCC BAA-835. The substrate spectrum of all three enzymes was analyzed and the results indicated a preference for different galactosidic linkages for each hydrolase. All preferred target structures are prevalent within mucins of the colonic habitat of A. muciniphila. To check a potential function of the enzymes for the degradation of mucosal glycan structures, porcine stomach mucin was applied as a model substrate. In summary, we could confirm the involvement of all three β-galactosidases from A. muciniphila in the complex mucin degradation machinery of this important gut microbe. These findings could contribute to the understanding of the molecular interactions between A. muciniphila and its host on a molecular level.

肠道微生物Akkermansia（A.）muciniphila变得越来越重要，因为其患病率与人类不同的代谢紊乱和疾病成反比。该生物是肠道粘蛋白的高效降解剂，然后水解的聚糖化合物可以作为生物自身或肠道微生物群其他成员的碳源，通过交叉进料。尽管它对宿主的健康和微生物群组成很重要，但确切的粘蛋白降解机制仍不清楚。在这项研究中，我们从A中鉴定并鉴定了三种胞外β-半乳糖苷酶（Amuc_0771，Amuc_0824和Amuc_1666）。墨菲ATCC BAA-835。分析了所有三种酶的底物谱，结果表明每种水解酶均偏爱不同的半乳糖苷键。所有优选的靶结构在粘液曲霉的结肠栖息地的粘蛋白中普遍存在。为了检查酶对粘膜聚糖结构降解的潜在功能，将猪胃粘蛋白用作模型底物。总而言之，我们可以证实粘液曲霉的所有三个β-半乳糖苷酶都参与了这一重要肠道微生物的复杂粘蛋白降解机制。这些发现可能有助于在分子水平上理解粘菌曲霉与其宿主之间的分子相互作用。