LhSiase1-catalyzed transglycosylation: unlocking the bioactive potential of bird's nest fragments for sialylated oligosaccharides synthesis.

Human milk oligosaccharides (HMOs) comprise a diverse array of structurally complex glycans, among which 3'-sialyllactose (3'-SL) is a predominant bioactive sialylated oligosaccharide. In this study, a novel sialidase LhSiase1 from Lactobacillus helsingborgensis was characterized and applied in a one-pot hydrolysis-transglycosylation process to produce 3'-SL from cost-effective glycoprotein sources. LhSiase1 showed optimal activity at 45 °C and pH 5.0, and demonstrated efficient transglycosylation with a hydrolysis/transglycosylation ratio (RH/T) of 2.27, converting sialic acid from casein glycomacropeptide (cGMP) into 3'-SL with a yield of 4.17 mg/mL. Importantly, it also transformed high-molecular-weight sialylglycoproteins from edible bird's nest fragments into 3'-SL at a yield of 2.28 mg/mL, thereby enhancing their bioavailability and potential for nutritional uptake. Furthermore, a practical instant powder formulation was developed, enabling equipment-free, in-situ 3'-SL synthesis upon hydration. This ready-to-use strategy offers a scalable route to produce bioactive 3'-SL for functional foods and nutraceuticals aimed at improving human health.