Background & Inspiration

The Problem We Want to Solve

Milk and dairy products are essential for human health, as they provide high-quality protein, calcium, and a balanced mix of nutrients. However, two major challenges limit their consumption:

• Lactose Intolerance – Approximately 70% of adults worldwide have varying degrees of lactose intolerance due to low lactase activity. Consuming milk often leads to symptoms such as bloating, abdominal pain, or diarrhea, which discourages further consumption.
• Excess Sugar Intake – Milk naturally contains around 4.8% lactose, which contributes significantly to daily sugar intake. Excessive sugar consumption is strongly associated with obesity, diabetes, and cardiovascular diseases.

Why Is This Problem Important?

Dairy products are too nutritionally valuable to be excluded from people’s diets. If we can make dairy products more digestible and healthier, we will not only help lactose-intolerant individuals but also align with global "sugar reduction" initiatives in the food industry. Developing low-lactose and low-sugar dairy products will expand access to nutritious foods while addressing pressing public health concerns.

Our Inspiration

• Industry Demand: The dairy industry is actively seeking technologies that can reduce lactose and sugar content while preserving the taste and nutritional value of products.
• Scientific Foundation: Research has demonstrated that β-T-galactosidase can both break down lactose and synthesize prebiotic galactooligosaccharides (GOS). Meanwhile, glucose oxidase (GOD) can convert glucose into gluconic acid, thereby lowering sugar content.
• iGEM Spirit: Many previous iGEM teams have addressed issues in the food and health sectors. Inspired by their innovative approaches, we aim to apply synthetic biology to a daily consumable—milk.

Project Design

To address these issues, we have designed a two-enzyme system using recombinant expression technology to create a healthier dairy product:

1. Transgalactosylation-active β-T-galactosidase (EC 3.2.1.23):
   • Breaks down lactose into glucose and galactose.
   • Produces galactooligosaccharides (GOS), which act as prebiotics, supporting gut health.
2. Glucose oxidase (GOD):
   • Converts the glucose generated in the first step into gluconic acid.
   • This reaction reduces sugar content while maintaining the nutritional value of the dairy product.

This design achieves three synergistic effects:

• Alleviates lactose intolerance by degrading lactose,
• Reduces carbohydrate intake by eliminating glucose,
• Enhances prebiotic functionality through the production of GOS and gluconic acid. Collectively, these enzymes enable the following:
• Eliminate most lactose → making the product suitable for lactose-intolerant individuals;
• Reduce total sugar content → supporting weight management and diabetes prevention.
• Enrich GOS content → adding functional dietary fiber to promote gut health. In short, we can tranform ordinary milk into a low-lactose, low-sugar and high-fiber functional dairy product.

Fig 1. Schematic diagram of the enzymatic reaction process

Goal

Our project aims to make dairy products more digestible for lactose-intolerant populations and reduce sugar intake without compromising taste or nutrition. We aim to develop a next-generation dairy product with the following characteristics:

• Low-lactose: Safe for individuals with lactose intolerance,
• Low-sugar: Reduced glucose content, aligning with modern dietary needs,
• Prebiotic-enriched: Containing GOS and gluconic acid to improve gut health. Ultimately, the products we envision include lactose-reduced milk, yogurt, and whey protein beverages—products that combine health benefits for consumers with scalable industrial applicability.

Fig 2. Schematic diagram of the overall goals of the functional dairy product.

References and Sources

1. Gosling, A., Stevens, G. W., Barber, A. R., Kentish, S. E., & Gras, S. L. (2010). Recent advances refining galactooligosaccharide production from lactose. Food Chemistry, 121(2), 307–318.
2. Cramer, J. F., Kjaer, K. H., Yde, C. C., Wichmann, J., Jensen, H. M., Kortman, G. A. M., Dellomonaco, C., & Ewert, J. (2025). β-T-galactosidase from Bifidobacterium bifidum for improved in situ synthesis of GOS-oligomers with prebiotic effects. International Dairy Journal, 163, 106164.
3. Qin, Z., Li, S., Huang, X., Kong, W., Yang, X., Zhang, S., Cao, L., & Liu, Y. (2019). Improving galactooligosaccharide synthesis efficiency of β-T-galactosidase Bgal1-3 by reshaping the active site with an intelligent hydrophobic amino acid scanning. Journal of Agricultural and Food Chemistry, 67(40), 11158–11166.
4. Bonnin, E., & Thibault, J.-F. (1996). Galactooligosaccharide production by transfer reaction of an exogalactanase. Enzyme and Microbial Technology, 19(2), 99–106.
5. Khatami, S. H., Vakili, O., Ahmadi, N., Soltani Fard, E., Mousavi, P., Khalvati, B., Maleksabet, A., Savardashtaki, A., & Taheri-Anganeh, M., & Movahedpour, A. (2022). Glucose oxidase: Applications, sources, and recombinant production. Biotechnology and Applied Biochemistry, 69(3), 939–950.