A quantitative analysis of hydrogen production efficiency of the extreme thermophile Caldicellulosiruptor owensensis OL

Research output: Contribution to journalArticle

Abstract

Caldicellulosiruptor owensensis strain OLT (DSM 13100) is an obligately anaerobic, extreme
thermophilic bacterium that is capable of utilizing a broad range of carbohydrates and
producing H2 as a metabolic by-product. The performance of C. owensensis on glucose and
xylose was analyzed in lab-scale bioreactors to assess its potential use in biohydrogen
production. Acetate, H2, and CO2 were the main end products during exponential growth of
the organism on either sugar. Lactate production was triggered during the transition into
the stationary phase and was associated with an increase in the levels of specific L-lactate
dehydrogenase activity. In addition, minor amounts of ethanol and propionate could be
detected. H2 and acetate yields were lower on xylose than on glucose, marking an opposite
trend to biomass and lactate yields. The influence of elevated H2 partial pressure on
product distribution was more dramatic in xylose-fermenting cultures. Replacement of
yeast extract in the medium with a standard vitamins solution improved H2 yield on both
sugars, where it reached 100% of the theoretical maximum, i.e. 4 mol per mol hexose, on
glucose. By using the defined medium, both the maximum specific growth rate and the
maximum volumetric H2 production rate of C. owensensis increased significantly on glucose
and almost doubled on xylose. Screening other sugars besides glucose and xylose revealed
a clear sugar-dependent product-distribution pattern and a direct correlation between
biomass and lactate yields, which might be explained considering energy metabolism
of the cells. The organism is proposed as a new candidate for biohydrogen production at
high yields.

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Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Industrial Biotechnology

Keywords

  • Biohydrogen Extreme thermophile Caldicellulosiruptor owensensis Batch mode H2 partial pressure Lactate formation Defined medium
Original languageEnglish
Pages (from-to)1128-1137
JournalInternational Journal of Hydrogen Energy
Volume35
Issue number3
Publication statusPublished - 2010
Publication categoryResearch
Peer-reviewedYes

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