Product selectivity shifts in Clostridium thermocellum in the presence of compressed solvents

Jason A. Berberich, Barbara L. Knutson, Herbert J. Strobel, Sefa Tarhan, Sue E. Nokes, Karl A. Dawson

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Organic solvents have been shown to affect the activity and selectivity of enzymes and whole cells in biphasic and nearly anhydrous systems. The choice of supercritical solvents and operating conditions may be used to vary the rates and selectivities of enzymes. Experiments were conducted to assess the impact of compressed nitrogen, ethane, and propane on the product selectivity of whole cell biocatalysts. The anaerobic thermophilic bacterium Clostridium thermocellum, which produces ethanol, acetate, and lactate, was used in the biphasic incubations. Compressed solvents lead to an increase in the ratio of ethanol to acetate produced by the organism. Furthermore, lactate formation was decreased in the presence of compressed and liquid solvents. The reduction in lactate formation is associated with a simultaneous reduction in the rate of cellobiose uptake by the microorganism. These results support the claim that incompatible solvents may affect the membrane and membrane transport systems of the microorganism. Finally, this work shows the potential for the manipulation of the product selectivity of whole cell biocatalysts by tuning solvent properties.

Original languageEnglish
Pages (from-to)4500-4505
Number of pages6
JournalIndustrial and Engineering Chemistry Research
Issue number12
StatePublished - 2000

ASJC Scopus subject areas

  • Chemistry (all)
  • Chemical Engineering (all)
  • Industrial and Manufacturing Engineering


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