Glucose, galactose and raffinose can all be used as carbon sources for Saccharomyces cerevisiae and Pichia pastoris. Glucose is the most commonly adopted carbon source for yeasts with high utilization efficiency and rapid yeast proliferation. However, the presence of glucose represses galactose-induced protein expression. Accordingly, glucose must not be supplemented into culture medium during experiments of galactose-induced protein expression in yeast.Galactose can be added to yeast medium as an inducer to trigger target protein expression. Nevertheless, Saccharomyces cerevisiae metabolizes galactose with very low efficiency. Certain yeast strains such as InvSc1 exhibit retarded growth or even fail to propagate when galactose is the sole carbon source.Raffinose serves as a highly efficient carbon source for yeast and does not interfere with galactose-mediated protein induction. Therefore, to accelerate cell growth and boost protein yield in galactose-induced yeast expression systems, 1% raffinose is typically incorporated into the culture medium.
Product Composition:
| Product Name | Item No. | Product Component | Molecular Formula/CAS No./Molecular Weight | Formula per Liter | Sterilization Method | | Glucose Solution (50%, Sterile-Filtered) | G1524580 | D(+)-Glucose | C₆H₁₂O₆/50-99-7/180.16 | 500 g | 0.22 μm Filtration | | Galactose Solution (20%, Sterile-Filtered) | G1524581 | D(+)-Galactose | C₆H₁₂O₆/59-23-4/180.16 | 200 g | 0.22 μm Filtration | | Raffinose Solution (20%, Sterile-Filtered) | R1524582 | D-Raffinose | C₁₈H₃₂O₁₆·5H₂O/512-69-6/504.44 | 200 g | 0.22 μm Filtration |
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Operating Instructions:
1. Pour plates: Melt yeast solid medium in a microwave oven or after autoclaving, then cool it down below 70°C. Add 20 mL of 50% glucose solution to every 500 mL medium, mix well and pour plates.
2. Yeast liquid medium: Autoclave yeast liquid medium and cool it below 70°C. Add 20 mL of 50% glucose solution, or 50 mL of 20% galactose solution to each 500 mL medium. Alternatively, add 50 mL of 20% galactose solution together with 25 mL of 20% raffinose solution.
3. The working concentration of glucose in yeast medium is 2%, galactose is 2%, and raffinose is 1%.
Precautions:
1. Unopened sugar solutions can be stored at room temperature for 1 year. For long-term storage, keep the product at -20°C. Discontinue use if contamination is detected after opening. Raffinose cannot be autoclaved at high temperature, as high-temperature sterilization will produce a small amount of glucose which inhibits protein expression.
2. This product is for research use only. It must not be applied to medicine, clinical diagnosis and treatment, food, cosmetics or other fields, and shall not be stored in residential areas.
3. Our company shall not be liable for any accidents caused by improper use of this product.
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