03/24/2026
By Danielle Fretwell

The Francis College of Engineering, Department of Biomedical Engineering & Biotechnology, invites you to attend a Doctoral Dissertation defense by Jiansong Qin on: "Metabolic engineering of yarrowia lipolytica for high-yield production of omega-3 EPA from waste cooking oil."

Candidate Name: Jiansong Qin
Degree: Doctoral
Defense Date: Thursday, April 2, 2026
Time (from/to): 10 - 11 a.m.
Location: Perry 315

Committee:

  • Advisor: Dongming Xie, Associate Professor, Chemical Engineering, University of Massachusetts Lowell
  • Hal Alper, Professor, McKetta Department of Chemical Engineering, University of Texas Austin
  • Carl Lawton, Associate Professor, Chemical Engineering, University of Massachusetts Lowell
  • Seongkyu Yoon, Professor, Chemical Engineering, University of Massachusetts Lowell
  • Quinn Zhu, Technical Fellow, International Flavors & Fragrances

Brief Abstract:
This research engineered Yarrowia lipolytica to produce eicosapentaenoic acid (EPA) using Waste Cooking Oil (WCO) as a cost-effective carbon source. While WCO provides direct lipid precursors, it initially triggered lipotoxicity due to excess Free Fatty Acid (FFA) accumulation. We knocked out the intracellular lipase Tgl4 to overcome this challenge. To harness the extra carbon flux provided by the WCO feed, we developed a high-strength promoter system ("pUSY") to efficiently express key enzymes coupled with lipid synthesis. Then, we decoupled cofactor competition between Fatty Acid Synthesis (FAS) and Fatty Acid Desaturation (FAD) by engineering ER-localized NADH-dependent reductases. This improved both FAS and FAD, thereby increasing total lipid content. Ultimately, we identified the Lands cycle as the critical bottleneck. Overexpressing LPCAT in the Y8412 strain resolved toxicity and restored metabolic cycling. The final strain achieved an EPA content of 40.7%, a total lipid content of 67.8%, and an EPA yield of 27.6% per Dry Cell Weight (DCW).