Abstract
Polyolefins derived from plastic wastes are recalcitrant for biological upcycling. However, chemical depolymerization of polyolefins can generate depolymerized plastic (DP) oil, comprising of a complex mixture of saturated, unsaturated, even, and odd hydrocarbons suitable for biological conversion. While DP oil contains a rich carbon and energy source, it is inhibitory to cells. Understanding and harnessing robust metabolic capabilities of microorganisms to upcycle the hydrocarbons in DP oil, both naturally and unnaturally occurring, into high-value chemicals are limited. Here, we discovered that an oleaginous yeast, Yarrowia lipolytica, undergoing short-term adaptation to DP oil robustly utilized a wide range of hydrocarbons for cell growth and production of citric acid and neutral lipids. When growing on hydrocarbons, Y. lipolytica partitioned into planktonic and oil-bound cells with each exhibiting distinct proteomes and amino acid distributions invested in establishing these proteomes. Significant proteome reallocation toward energy and lipid metabolism, belonging to 2 of the 23 Eukaryotic Orthologous Groups classes C and I, enabled robust growth of Y. lipolytica on hydrocarbons, with n-hexadecane as the preferential substrate. This investment was even higher for growth on DP oil where classes C and I were ranked one and two, respectively, and many associated proteins and pathways were expressed and upregulated including the hydrocarbon degradation pathway, Krebs cycle, glyoxylate shunt and, unexpectedly, propionate metabolism. However, a reduction in proteome allocation for protein biosynthesis, at the expense of the observed increase toward energy and lipid metabolisms, might have caused the inhibitory effect of DP oil on cell growth.
Original language | English |
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Journal | mSystems |
Volume | 8 |
Issue number | 6 |
DOIs | |
State | Published - Dec 2023 |
Funding
This research is supported in part by the ORII Seed Fund at The University of Tennessee, Knoxville (to C.T.T., B.K., S.L., and R.J.G.), and the DOE BER Genomic Science Program (DE-SC0019412 to C.T.T. and R.J.G.). The views, opinions, and/or contained in this article are those of the authors and should not be interpreted as representing the views or policies, either expressed or implied, of the funding agencies. The mention of trade names or commercial products in this publication is solely for the purpose of providing information and does not imply a recommendation or endorsement by the funding agencies.
Keywords
- 1-alkenes
- LLDPE
- Yarrowia lipolytica
- adaptive laboratory evolution
- catalytic depolymerization
- citric acid
- n-alkanes
- n-hexadecane
- neutral lipids
- plastic waste
- polyethylene
- proteome
- proteome reallocation
- upcycling