Microbial production of various biofuel components is well known in the art and may use isolated naturally occurring microorganisms, or genetically engineered microorganisms that have one or more genes added or modified/deleted to improve product yield.
For example, GB2018822B teaches use of methylotrophic bacteria to produce various hydrocarbon products from methane as feedstock. While such methods advantageously allow use of aerobic culture conditions, yields are often less than desirable and the culture medium typically requires the presence of one or more methyl-radical donating carbon-containing compounds.
In other examples, anaerobic bacteria have been used to convert carbon monoxide to alcohols, including butanol, ethanol, and acetic acid, and typical microorganisms include those of the genus Clostridium (e.g., Clostridium lungdahlii, including those described in WO 00/68407, EP 117309, U.S. Pat. Nos. 5,173,429, 5,593,886, and 6,368,819, WO 98/00558 and WO 02/08438, and Clostridium autoethanogenum (Aribini et al, Archives of Microbiology 161: pp 345-351)). Other Clostridial species using syngas are described in US 2010/0203606 and 2007/0275447 for production of ethanol from carbon monoxide. Further suitable bacteria include those of the genus Moorella, including Moorella sp HUC22-1, (Sakai et al, Biotechnology Letters 29: pp 1607-1612), and those of the genus Carboxydothermus (Svetlichny, V. A., Sokolova, T. G. et al (1991), Systematic and Applied Microbiology 14: 254-260). However, the media composition in many cases is relatively complex, and culture conditions are often difficult to reproduce.
To reduce complexity for media, carbon dioxide may be added to the medium while maintaining free acid concentration below a threshold value to so improve production flow as previously shown in WO2009/114127 where selected (typically Clostridial) microorganisms produce ethanol using syngas as a feedstock. However, anaerobic culture conditions must be maintained during the fermentation in most cases, which will once more increase operational complexity. Further media modifications are described in US 2011/0236919 in which a surface tension active compound is used to control quantities of the dissolved gases.
Likewise, WO 2011/139804 describes various hybrid production processes in which oxyhydrogen microorganisms (and in particular purple non-sulfur photosynthetic bacteria) are employed for non-photosynthetic carbon capture and conversion of inorganic and/or C1 carbon sources into useful organic compounds. However, the production set-up for biofuel components in this process is yet again relatively complex.
Thus, there is still a need to provide improved systems and methods for production of biofuel components, and particularly alcohols, aldehydes, and acids using microorganisms in a conceptually simple and effective manner using low-molecular weight gases and mixtures thereof.