摘要Laminarin oligosaccharides(LOSs)with a specific degree of polymerization prepared through the laminarin degradation via laminarinase present more significant nutritional functions and application values.Human intestinal bacteria are promising potential producers of novel carbohydrate-active enzymes with unique properties.Here,a novel glycoside hydrolase family 128(GH128)laminarinase OUC-BsLam26 from the intestinal bacterium Bacteroides sp.CBA7301 was heterologously expressed and characterized.The recombinant OUC-BsLam26 with a molecular mass of 49.86 kDa exhibits highest activity(6.60 U/mg)at 45 ℃ and pH 6.0,which shows noticeable temperature and pH stability.The purified OUC-BsLam26 could degrade laminarin via an endo-type mode with the generation of laminaripentaose,laminaritetraose.laminaritriose,and laminaribiose,among them,laminaritetraose is the principal product,which accounts for 45.25％of the total products,which is significantly different from the reported GH128 laminarinases.The minimum recognition substrate of OUC-BsLam26 is laminarihexaose.Furthermore,OUC-BsLam26 also could catalyze the transglycosylation process with the production of some novel glycosides.Altogether,the intestinal bacterium Bacteroides sp.CBA7301 contains laminarinase with unique product composition and OUC-BsLam26 is a hopeful bio-catalyst with the potential to produce laminaritetraose and some novel glycosides.