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Open AccessArticle

Gas Fermentation Enhancement for Chemolithotrophic Growth of Cupriavidus necator on Carbon Dioxide

Hawaii Natural Energy Institute, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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Fermentation 2018, 4(3), 63; https://doi.org/10.3390/fermentation4030063
Received: 7 July 2018 / Revised: 3 August 2018 / Accepted: 7 August 2018 / Published: 9 August 2018
(This article belongs to the Special Issue Bioprocess and Fermentation Monitoring)
Cupriavidus necator, a facultative hydrogen-oxidizing bacterium, was grown on carbon dioxide, hydrogen, and oxygen for value-added products. High cell density and productivity were the goal of gas fermentation, but limited by gas substrates because of their low solubility in the aqueous medium solution. Enhancement of gas fermentation was investigated by (i) adding n-hexadecane as a gas vector to increase the volumetric mass transfer coefficient (kLa) and gas solubility, (ii) growing C. necator under a raised gas pressure, and (iii) using cell mass hydrolysates as the nutrients of chemolithotrophic growth. In contrast to previous studies, little positive but negative effects of the gas vector were observed on gas mass transfer and cell growth. The gas fermentation could be significantly enhanced under a raised pressure, resulting in a higher growth rate (0.12 h−1), cell density (18 g L−1), and gas uptake rate (200 mmole L−1 h−1) than a fermentation under atmospheric pressure. The gain, however, was not proportional to the pressure increase as predicted by Henry’s law. The hydrolysates of cell mass were found a good source of nutrients and the organic nitrogen was equivalent to or better than ammonium nitrogen for chemolithotrophic growth of C. necator on carbon dioxide. View Full-Text
Keywords: CO2 fixation; hydrogen-oxidizing bacteria; Cupriavidus necator; chemolithotrophic growth; gas vector; pressured gas fermentation; cell mass hydrolysates CO2 fixation; hydrogen-oxidizing bacteria; Cupriavidus necator; chemolithotrophic growth; gas vector; pressured gas fermentation; cell mass hydrolysates
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MDPI and ACS Style

Yu, J.; Munasinghe, P. Gas Fermentation Enhancement for Chemolithotrophic Growth of Cupriavidus necator on Carbon Dioxide. Fermentation 2018, 4, 63.

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