Effect of culture conditions on hydrogen production by Thermoanaerobacter strain AK68

Ziva Vipotnik*, Jan Eric Jessen, Sean Michael Scully, Johann Orlygsson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Thermoanaerobacter strain AK68, isolated from a hot spring in Iceland, was investigated for hydrogen production from sugars. Strain AK68 is most closely related to Thermoanaerobacter thermohydrosulfuricus (99.9% similarity). The strain has a temperature optimum between 65 C and 70 C and a pH optimum between pH 7.0 and 8.0. The strain degraded the majority of substrates examined including common hexoses and disaccharides as well as xylose but not arabinose or starch. Various environmental variables were investigated to gain a deeper understanding of the factors that are of importance for hydrogen production since the strain shows inhibition at relatively low initial glucose concentrations. Factors investigated included initial glucose concentration, phosphate buffer concentration, liquid-gas phase ratio, effect of various external electron acceptors, and different initial pH values. Substrate utilization was shown to be inhibited by increased partial pressure of hydrogen, as evidenced by increased utilization of glucose using electron scavenging systems and manipulation of the liquid-gas phase ratio, rather than substrate or end product inhibition.

Original languageEnglish
Pages (from-to)181-189
Number of pages9
JournalInternational Journal of Hydrogen Energy
Issue number1
Publication statusPublished - 5 Jan 2016

Bibliographical note

Publisher Copyright:
© 2015 Hydrogen Energy Publications, LLC.

Other keywords

  • Biofuel
  • Biohydrogen
  • Partial pressure of hydrogen
  • Substrate inhibition
  • Thermoanaerobes


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