Campus Units

Chemical and Biological Engineering, Microbiology, Ames Laboratory, NSF Engineering Research Center for Biorenewable Chemicals

Document Type

Article

Research Focus Area

Biorenewables

Publication Version

Accepted Manuscript

Publication Date

9-2021

Journal or Book Title

Metabolic Engineering

Volume

67

First Page

428

Last Page

442

DOI

10.1016/j.ymben.2021.08.002

Abstract

Microbial synthesis of wax esters (WE) from low-cost renewable and sustainable feedstocks is a promising path to achieve cost-effectiveness in biomanufacturing. WE are industrially high-value molecules, which are widely used for applications in chemical, pharmaceutical, and food industries. Since the natural WE resources are limited, the WE production mostly rely on chemical synthesis from rather expensive starting materials, and therefore solution are sought from development of efficient microbial cell factories. Here we report to engineer the yeast Yarrowia lipolytica and bacterium Escherichia coli to produce WE at the highest level up to date. First, the key genes encoding fatty acyl-CoA reductases and wax ester synthase from different sources were investigated, and the expression system for two different Y. lipolytica hosts were compared and optimized for enhanced WE production and the strain stability. To improve the metabolic pathway efficiency, different carbon sources including glucose, free fatty acid, soybean oil, and waste cooking oil (WCO) were compared, and the corresponding pathway engineering strategies were optimized. It was found that using a lipid substrate such as WCO to replace glucose led to a 60-fold increase in WE production. The engineered yeast was able to produce 7.6 g/L WE with a yield of 0.31 (g/g) from WCO within 120 h and the produced WE contributed to 57% of the yeast DCW. After that, E. coli BL21(DE3), with a faster growth rate than the yeast, was engineered to significantly improve the WE production rate. Optimization of the expression system and the substrate feeding strategies led to production of 3.7–4.0 g/L WE within 40 h in a 1-L bioreactor. The predominant intracellular WE produced by both Y. lipolytica and E. coli in the presence of hydrophobic substrates as sole carbon sources were C36, C34 and C32, in an order of decreasing abundance and with a large proportion being unsaturated. This work paved the way for the biomanufacturing of WE at a large scale.

Comments

This is a manuscript of an article published as Soong, Ya-Hue Valerie, Le Zhao, Na Liu, Peng Yu, Carmen Lopez, Andrew Olson, Hsi-Wu Wong, Zengyi Shao, and Dongming Xie. "Microbial synthesis of wax esters." 67 Metabolic Engineering (2021): 428-442. DOI: 10.1016/j.ymben.2021.08.002. Posted with permission.

Copyright Owner

International Metabolic Engineering Society

Language

en

File Format

application/pdf

Available for download on Saturday, August 13, 2022

Published Version

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