10/09/2024
By Elif Kurt

The Francis College of Engineering, Department of Chemical Engineering, invites you to attend a doctoral proposal defense by Elif Kurt on “Integrating Continuous Fermentation and CO2-Recycling For Enhanced Lipid Production."

Candidate Name: Elif Kurt
Degree: Doctoral
Defense Date: Wednesday, Oct. 23, 2024
Time: 1 - 3 p.m.
Location: Perry 315

Thesis/Dissertation Title: Integrating Continuous Fermentation and CO2-Recycling For Enhanced Lipid Production

Advisor: Dongming Xie, Ph.D., Chemical Engineering, UMass Lowell

Committee Members:

  • Carl Lawton, Ph.D., Chemical Engineering, UMass Lowell
  • Hsi-Wu Wong, Ph.D., Chemical Engineering, UMass Lowell
  • Jin Xu, Ph.D., Chemistry, UMass Lowell

Brief Abstract:
Microbial biomanufacturing, with its minimal carbon footprint, offers an eco-friendly alternative to traditional industrial approaches, exploiting abundant lignocellulosic and feedstocks such as pentose and hexose sugars. Incorporating lignocellulosic feedstocks, particularly glucose, in microbial factories requires balancing the optimal carbon distribution for cell growth while ensuring the desired product yield. A significant portion of carbon is disbursed as CO2 during biosynthesis, undermining the key advantage of biomanufacturing in reducing greenhouse gas emissions and increasing product yield. Within this framework, the first part of my research proposes the transformation of 'lost' carbon in the form of CO2 into value by using products like formate and acetate (C1 and C2 chemicals), which various electrochemical, thermal, or catalytic methods can already obtain. These substrates may shorten the pathways through lipid production and result in less carbon loss, which aims to design a new fermentation process that uses CO2-derived C1/C2 chemicals together with glucose as the co-substrates for biomanufacturing. Strategies such as constituting new pathways by metabolic engineering efforts and co-feeding two or more substrates will be attempted to achieve the zero-carbon release approach. In the meantime, optimization of the fermentation for batch and fed-batch processes is cumbersome. Continuous fermentation with a stable strain would ease the optimization process without requiring numerous separate runs. Two-stage continuous fermentation emerges as a promising technique especially. During this process, microbes are nurtured in a nitrogen-rich environment to promote cell growth. Once the optimal cell density is achieved, they are subjected to nitrogen limitation, which drives lipid accumulation. Regarding the preliminary data, even single-stage continuous fermentation has considerably increased productivity and biomass concentration in engineered strains of Yarrowia lipolytica. To further harness the sustainability of this method, this study explored a two-stage process. My work will further focus on optimizing the intricacies of fermentation parameters, media, and downstream processing, which can affect the full potential of microbial lipid production by continuous biomanufacturing. Adaptive laboratory evolution will also be employed as an effective strategy alongside metabolic engineering to optimize this process. In conclusion, while microbial cell factories hold immense potential for sustainable biomanufacturing and lipid production, their efficiency hinges on addressing the challenges in continuous fermentation and innovative strategies in carbon utilization.