Integrated bioprocess for conversion of gaseous substrates to liquids
Name
Hu-2016-Integrated bioproces.pdf
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Author(s)
Hu, Peng
Chakraborty, Sagar
Kumar, Amit
Woolston, Benjamin Michael
Liu, Hongjuan
Emerson, David Frederic
Stephanopoulos, Gregory
Date Issued
January 2016
Journal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences (U.S.)
Citation
Hu, Peng; Chakraborty, Sagar; Kumar, Amit; Woolston, Benjamin; Liu, Hongjuan; Emerson, David and Stephanopoulos, Gregory “Integrated Bioprocess for Conversion of Gaseous Substrates to Liquids.” Proceedings of the National Academy of Sciences 113, no. 14 (March 2016): 3773–3778 © 2016 National Academy of Sciences
Version
Final published version
Abstract
In the quest for inexpensive feedstocks for the cost-effective production of liquid fuels, we have examined gaseous substrates that could be made available at low cost and sufficiently large scale for industrial fuel production. Here we introduce a new bioconversion scheme that effectively converts syngas, generated from gasification of coal, natural gas, or biomass, into lipids that can be used for biodiesel production. We present an integrated conversion method comprising a two-stage system. In the first stage, an anaerobic bioreactor converts mixtures of gases of CO₂ and CO or H₂ to acetic acid, using the anaerobic acetogen Moorella thermoacetica. The acetic acid product is fed as a substrate to a second bioreactor, where it is converted aerobically into lipids by an engineered oleaginous yeast, Yarrowia lipolytica. We first describe the process carried out in each reactor and then present an integrated system that produces microbial oil, using synthesis gas as input. The integrated continuous bench-scale reactor system produced 18 g/L of C16-C18 triacylglycerides directly from synthesis gas, with an overall productivity of 0.19 g⋅L⁻¹⋅h⁻¹ and a lipid content of 36%. Although suboptimal relative to the performance of the individual reactor components, the presented integrated system demonstrates the feasibility of substantial net fixation of carbon dioxide and conversion of gaseous feedstocks to lipids for biodiesel production. The system can be further optimized to approach the performance of its individual units so that it can be used for the economical conversion of waste gases from steel mills to valuable liquid fuels for transportation.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
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DOI of Published Version
https://doi.org/10.1073/pnas.1516867113
