Enzymatic conversion of insoluble yeast β-glucans into low-molecular-weight, water-soluble prebiotics using enzyme cocktails derived from natural rubber serum

Yeast and mushroom β-(1,3/1,6)-glucans are well known for immunomodulatory and anti-inflammatory activities, yet their prebiotic potential remains limited by high molecular weight (MW), rigid triple-helical conformation, and poor solubility, which restrict microbial fermentation. Here, we developed a sustainable valorization strategy using enzyme cocktails derived from natural rubber serum (NRS), enriched in crude endo -β-1,3-glucanase, to depolymerize insoluble β-glucans (IBGs) from Saccharomyces cerevisiae into hydrolyzed β-glucans (HBGs). Enzymatic processing generated low-MW HBGs (~5.6 kDa) with markedly improved water solubility and modified surface morphology. HBGs exhibited triple-helical structures with enhanced antioxidant activity (DPPH • , ABTS •+ , H 2 O 2 scavenging, and ferric reducing assays) and resisted simulated gastrointestinal digestion. In vitro fermentation demonstrated selective stimulation of probiotic growth, particularly Lacticaseibacillus rhamnosus , with culture supernatants showing broad-spectrum antimicrobial activity. Metabolomic analysis revealed distinct metabolic shifts and increased short-chain fatty acid (SCFAs) production, notably propionate and butyrate. These findings establish NRS-derived enzymatic bioprocessing as a green platform for producing low-MW, water-soluble β-glucans with improved fermentability and multifunctional bioactivity, supporting their development as candidate prebiotic-oriented gut-health ingredients.