Galactooligosaccharides (GOS) are a class of prebiotic carbohydrates composed of 2 to 8 galactose units linked together and often terminated with a glucose molecule. GOS have attracted significant attention for their health-promoting properties, including the regulation of gut microbiota, promotion of infant health, immune modulation, laxative effects, and potential metabolic benefits. Widely utilized in functional foods, infant formulas, dairy products, and dietary supplements, GOS occur naturally in human milk and are primarily industrially produced through the enzymatic conversion of lactose. β-Galactosidase is a crucial enzyme in GOS bioproduction, which exhibits dual functions of hydrolysis and transglycosylation. In this investigation, a novel β-galactosidase from Pseudomonas tritici SWRI145 (Pstr β-galactosidase) was characterized. Biochemical characterization revealed that the enzyme exhibits the highest activity at 50 °C and pH 7.5, with a specific activity of 331.9 U/mg against ONPG. Under optimal reaction conditions (40 °C, pH 8.0, 300 g/L lactose, 0.4 mg/mL enzyme), 134.3 g/L GOS were produced, corresponding to 44.8% GOS yield and 80% substrate conversion. LC-MS analysis confirmed that the main products were GOS with degrees of polymerization (DP) ranging from 2 to 4. To our knowledge, this is the first report of a Pseudomonas-derived β-galactosidase with demonstrated GOS synthesis capability, highlighting its potential for industrial application.
Jin et al. (Sat,) studied this question.
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