Bio-electrochemical activity of Clostridium ljungdahlii at different cathodic potentials
Typ
Examensarbete för masterexamen
Program
Publicerad
2021
Författare
Hadi, Fahim
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Humans are responsible for a large portion of the emissions of CO2 gas since the industrial
revolution. These emissions must decrease so that the increase of temperature should not
exceed an increase of 2 °C by the end of this century. Gas fermentation is a promising
technology that could reduce the emissions of CO2 into the atmosphere. Clostridium
ljungdahlii is an interesting anaerobic microorganism capable of CO2 fixation and produce
valuable chemicals such as ethanol. C. ljungdahlii is also known for the capability of
accepting electrons from an electrode in a bio-electrochemical system. The bio electrochemical activity of C. ljungdahlii was thus investigated at the cathodic potentials -
400, -600, -800 and -1000 mV. This was done by running biotic and abiotic bio electrochemical system experiments at the mentioned potentials, as well as serum flask
control experiments. The results were analysed by investigating product formation, growth,
pH, current consumption, and the mechanism of electron transfer in the bio-electrochemical
system reactors. No planktonic cell growth was observed in the optical density
measurements, but CO2 fixation by C. ljungdahlii in a bio-electrochemical system was
observed. C. ljungdahlii could in a bio-electrochemical system produce 2,3-butanediol at -
800 mV, and though not reproducible, also ethanol at -600 mV. C. ljungdahlii seem on the
other hand to consume formate at all potentials applied. The current consumption of C.
ljungdahlii was very low indicating that H2 could have been produced but was not consumed
by C. ljungdahlii.