11/22/2021
By Sokny Long

The Francis College of Engineering, Biomedical Engineering and Biotechnology Program, invites you to attend a doctoral dissertation defense by Ya-Hue Valerie Soong on “Cellular Engineering for Microbial Biomanufacturing of High-Value Products from Non-Sugar Raw Materials."

Ph.D. Candidate: Ya-Hue Valerie Soong
Defense Date: Monday, Dec. 6, 2021
Time: 2 to 4 p.m. EST
Location: This will be a virtual defense via Zoom. Those interested in attending should contact the student, YaHueValerie_Soong@student.uml.edu, and committee advisor, Dongming_Xie@uml.edu, at least 24 hours prior to the defense to request access to the meeting.

Committee Chair (Advisor): Dongming Xie, Associate Professor, Chemical Engineering Department, UMass Lowell

Committee Members:

  • Seongkyu Yoon, Professor, Chemical Engineering Department, UMass Lowell
  • Jin Xu, Professor, Chemistry Department, UMass Lowell
  • Carl Lawton, Associate Professor, Chemical Engineering Department, UMass Lowell
  • Hsi-Wu Wong, Associate Professor, Chemical Engineering Department, UMass Lowell

Brief Abstract:
The development of sustainable and economical biomanufacturing processes as alternatives to traditional petrochemical productions provides a promising solution to build the value chain on transformation from renewable, low-cost raw materials or waste feedstocks into value-added products for applications in fuel, chemical, food, and pharmaceutical industry. Sugars, either produced directly by sugar crops or indirectly derived from starch or cellulosic biomass, are currently the major starting material for biomanufacturing. However, there are some other economical and sustainable carbon sources can be utilized as the starting materials for biomanufacturing with the advantages of improving product yield, reducing environmental footprint, or lowering manufacturing cost. My thesis work focuses on two major non-sugar materials: plant oils (with annual production twice as much as sugars in the US) and plastic wastes such as the polyethylene terephthalate (PET) plastic waste, which has only 25% being recycled after its first use.

The first part of my research is to engineer the non-conventional yeast Yarrowia lipolytica to convert oils/fats into value-added products. The cell morphology was engineered to facilitate the utilization of the extracellular fatty acids and the bioconversion of the intracellular lipids into the high-value products. Wax ester, which can be used as biolubricants and cosmetics, is chosen as the product example for demonstration of the technology platform. The biosynthesis pathway for production of wax esters is being established and optimized. The engineered yeast was able to produce 7.6 g/L wax esters with a yield of 0.31 (g/g) from waste cooking oil within 120 h. The produced wax esters contributed to 57% of the yeast dry cell weight, which is so far the highest level reported. This work paved the way for the biomanufacturing of wax esters at a large scale.

The second part of my research is to explore the feasibility of biodegradation and bioconversion of PET plastic wastes. Several PET-hydrolyzing enzymes, including leaf-branch compost cutinase (LCC), PETase and MHETase, were cloned and heterologously expressed in Escherichia coli BL21(DE3). The PET-hydrolyzing enzymes were further engineered for enhanced PET degradation and/or capability of adsorption on the plastic surface. The engineered LCC successfully improved the depolymerization of commercial and post-consumer PET plastics into its monomers. Up to 100% degradation of PET samples within 96 h was achieved. This study not only opens up an exciting platform for efficient biodegradation and bioconversion of recyclable plastic wastes, but also provides potential bioremediation strategies for the treatment of PET or similar plastic wastes from terrestrial and marine sources.

All interested students and faculty members are invited to attend the online defense via remote access.