Syngas fermentation, also known as synthesis gas fermentation, is a microbial process. In this process, a mixture of hydrogen, carbon monoxide, and carbon dioxide, known as syngas, is used as carbon and energy sources, and then converted into fuel and chemicals by microorganisms. The main products of syngas fermentation include ethanol, butanol, acetic acid, butyric acid, and methane.
There are several microorganisms which can produce fuels and chemicals by syngas utilization. These microorganisms are mostly known as acetogens including Clostridium ljungdahlii, Clostridium autoethanogenum, Eurobacterium limosum, Clostridium carboxidivorans P7, Peptostreptococcus products, and Butyribacterium methylotrophicum.
Syngas fermentation process has advantages over a chemical process since it takes places at lower temperature and pressure, has higher reaction specificity, tolerates higher amounts of sulfur compounds, and does not require a specific CO:H2. On the other hand, syngas fermentation has limitations such as:
* Gas-liquid mass transfer limitation
* Low volumetric productivity, and
* Inhibition of organisms.