Multiple Strategies Enhance 7-Dehydrocholesterol Production from Kitchen Waste by Engineered Yarrowia lipolytica

Area of Science:

• Biotechnology
• Synthetic Biology
• Metabolic Engineering

Background:

• 7-Dehydrocholesterol (7-DHC) is a vital precursor for vitamin D3 synthesis.
• Microbial production of 7-DHC is gaining interest for sustainable synthesis.
• Existing methods for 7-DHC production face challenges in yield and sustainability.

Purpose of the Study:

• To develop a sustainable and green bioproduction route for 7-DHC using engineered yeast.
• To enhance 7-DHC yield from kitchen waste by optimizing metabolic pathways and fermentation conditions.
• To establish a high-titer microbial production system for 7-DHC.

Main Methods:

• Engineering *Yarrowia lipolytica* with modified mevalonate pathway genes and Δ24-dehydrocholesterol reductases.
• Optimizing fermentation medium components using response surface methodology.
• Scaling up production in a 5-L bioreactor using kitchen waste as a carbon source.

Main Results:

• Overexpression of mevalonate pathway genes increased 7-DHC titer from 21.8 to 145.6 mg/L.
• Medium optimization via response surface method boosted 7-DHC titer to 391.0 mg/L in shake flasks.
• A record 7-DHC titer of 3.5 g/L was achieved in a 5-L bioreactor using kitchen waste.

Conclusions:

• Engineered *Y. lipolytica* provides an efficient platform for 7-DHC bioproduction from waste lipids.
• The developed process offers a promising and sustainable alternative for industrial 7-DHC synthesis.
• This study demonstrates the potential of yeast metabolic engineering for valorizing waste streams into valuable compounds.