TY - JOUR
T1 - Coupling Gas Purging with Inorganic Carbon Supply to Enhance Biohydrogen Production with Clostridium thermocellum
T2 - Article No. 141028
AU - Kim, Changman
AU - Wolf, Isaac
AU - Dou, Chang
AU - Magnusson, Lauren
AU - Maness, Pin-Ching
AU - Chou, Katherine
AU - Singer, Steven
AU - Sundstrom, Eric
PY - 2023
Y1 - 2023
N2 - Clostridium thermocellum is a desirable biocatalyst for biohydrogen production, with a native ability to simultaneously saccharify cellulose and to metabolize released cellodextrins for hydrogen production. During fermentation with C. thermocellum, partial pressures of two gases - CO2 and H2 - are critical drivers of overall reaction kinetics. Biohydrogen production is enhanced by maintaining a low hydrogen partial pressure, while high concentrations of dissolved CO2 promote microbial biomass synthesis. Our study evaluates the inherent trade-offs between hydrogen stripping and inorganic carbon supply for optimized biohydrogen synthesis. We find that nitrogen sparging at low flow rates increases hydrogen production when compared with an equivalent nitrogen overlay, but that high rates of nitrogen sparging inhibit cell growth and hydrogen production. Decreasing dissolved hydrogen partial pressure via nitrogen sparging also lowers the production of reduced metabolites, including lactate and ethanol. To address potential stripping of inorganic carbon from the production medium, we supplemented CO2 to the sparging gas and co-optimized for gas flow rate and for the CO2 fraction of the sparging gas. Total hydrogen production increased from 50 mmol L-1 in the base condition, when the bioreactor was sparged with 0.1 LPM of pure nitrogen, to 181.3 mmol L-1 when sparged with 1.3 LPM of 33% CO2, demonstrating that biohydrogen production is highly sensitive to both parameters. Fine sensitivity of biohydrogen production to sparging conditions highlights the critical importance of bioreactor design and operation to achieve maximum H2 removal without compromising inorganic carbon supply to bacterial central metabolism.
AB - Clostridium thermocellum is a desirable biocatalyst for biohydrogen production, with a native ability to simultaneously saccharify cellulose and to metabolize released cellodextrins for hydrogen production. During fermentation with C. thermocellum, partial pressures of two gases - CO2 and H2 - are critical drivers of overall reaction kinetics. Biohydrogen production is enhanced by maintaining a low hydrogen partial pressure, while high concentrations of dissolved CO2 promote microbial biomass synthesis. Our study evaluates the inherent trade-offs between hydrogen stripping and inorganic carbon supply for optimized biohydrogen synthesis. We find that nitrogen sparging at low flow rates increases hydrogen production when compared with an equivalent nitrogen overlay, but that high rates of nitrogen sparging inhibit cell growth and hydrogen production. Decreasing dissolved hydrogen partial pressure via nitrogen sparging also lowers the production of reduced metabolites, including lactate and ethanol. To address potential stripping of inorganic carbon from the production medium, we supplemented CO2 to the sparging gas and co-optimized for gas flow rate and for the CO2 fraction of the sparging gas. Total hydrogen production increased from 50 mmol L-1 in the base condition, when the bioreactor was sparged with 0.1 LPM of pure nitrogen, to 181.3 mmol L-1 when sparged with 1.3 LPM of 33% CO2, demonstrating that biohydrogen production is highly sensitive to both parameters. Fine sensitivity of biohydrogen production to sparging conditions highlights the critical importance of bioreactor design and operation to achieve maximum H2 removal without compromising inorganic carbon supply to bacterial central metabolism.
KW - Avicel
KW - biohydrogen
KW - Clostridium thermocellum
KW - gas sparging
UR - http://www.scopus.com/inward/record.url?scp=85144954566&partnerID=8YFLogxK
U2 - 10.1016/j.cej.2022.141028
DO - 10.1016/j.cej.2022.141028
M3 - Article
SN - 1369-703X
VL - 456
JO - Biochemical Engineering Journal
JF - Biochemical Engineering Journal
ER -