System-Level Optimization to Improve Biofuel Potential via Genetic Engineering and Hydrothermal Liquefaction

Tao Dong, Wei Xiong, Nicholas Sweeney, Philip Pienkos, Jianping Yu, Bo Wang

Research output: Contribution to journalArticlepeer-review

5 Scopus Citations


The economic viability of biofuels and bioproducts depends on system-level optimization including biomass production and conversion. Hydrothermal liquefaction (HTL) can convert wet biomass such as microalgae into a biofuel intermediate (BFI) under elevated temperatures and pressure. An understanding of the impacts of biomass composition on BFI yield and quality can inform genetic engineering strategies in the improvement of biochemical composition for biofuel production. In this work, wild type cyanobacterium Synechocystis sp. PCC 6803 biomass was doped with various common cellular storage compounds in lab-scale HTL experiments. Doping with glycogen or polyhydroxybutyrate (PHB) significantly reduced BFI yields, while doping with triglycerides (TAG) or medium chain-length polyhydroxyalkanoate (mcl-PHA) increased BFI yield and quality. In light of these observations, a genetically engineered Synechocystis strain deficient in glycogen biosynthesis was cultivated to produce biomass for HTL, leading to a 17% increase in BFI yield. In addition, we built a multiphase component additivity (MCA) model that can predict BFI yield and quality with PHAs in the biomass. This work demonstrates an effective strategy to integrate strain development with downstream biomass conversion to maximize biofuel yield, with lessons applicable to microalgae as well as other biomass.

Original languageAmerican English
Pages (from-to)2753-2762
Number of pages10
JournalACS Sustainable Chemistry and Engineering
Issue number7
StatePublished - 2020

Bibliographical note

Publisher Copyright:
Copyright © 2020 American Chemical Society.

NREL Publication Number

  • NREL/JA-5100-74835


  • Biofuel intermediate (BFI)
  • Cyanobacteria
  • Genetic engineering
  • Hydrothermal liquefaction (HTL)
  • Microalgae
  • Polyhydroxyalkanoate


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