Clostridium acetobutylicum

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Clostridium acetobutylicum
Scientific classification
Kingdom: Bacteria
Division: Firmicutes
Class: Clostridia
Order: Clostridiale
Family: Clostridiaceae
Genus: Clostridium
Species: C. acetobutylicum

Clostridium acetobutylicum, included in the genus Clostridium, is a commercially valuable bacterium. It is sometimes called the "Weizmann Organism", after Chaim Weizmann, who in 1916 helped discover how C. acetobutylicum culture could be used to produce acetone, butanol, and ethanol from starch using the ABE process (Acetone Butanol Ethanol process) for industrial purposes such as gunpowder and Cordite (using acetone) production. The A.B.E. process was an industry standard until the late 1940s, when low oil costs drove more-efficient processes based on hydrocarbon cracking and petroleum distillation techniques. C. acetobutylicum also produces acetic acid (vinegar), butyric acid (a substance that smells like vomit), carbon dioxide, and hydrogen.

Anaerobic fermentation using C. acetobutylicum recently regained marked interest for use in vehicle biofuel production as a gasoline and diesel fuel replacement. This is because butanol, as produced by a fibrous bed bioreactor utilizing recent biotechnology co-developed by Environmental Energy Inc. and Ohio State University, produces the alcohol butanol as its primary output. The patented process using C. tyrobutyricum produces little acetone or ethanol, instead producing butyric acid and hydrogen, which is then pumped into another fibrous bed bioreactor where C. acetobutylicum converts the butyric acid into butanol, thus optimizing butanol production. The new process, then, obviates the A.B.E. process, making butanol production competitive with other biofuels with regard to both economics and energy production.

Pure butanol can be utilized in gasoline-powered cars without any modifications, producing similar mileage performance to gasoline but producing fewer NOx pollutants. If produced from a biomass source, there is no net carbon dioxide production.

Unlike yeast, which can digest sugar only into alcohol and carbon dioxide, C. acetobutylicum and many other Clostridia can digest whey, sugar, starch, lignin, cellulose fiber[dubious – discuss], and other biomass directly into butanol, propionic acid, ether, and glycerin. Apart from the need for temperature control, the A.B.E. synthesis process is relatively simple. The products are however, completely miscible in water at the low concentrations produced by fermentation. In addition there is an azeotrope formed by both ethanol and water as well as Butanol and water. The azeotropes as well as the low concentrations of product lead to a relatively complicated separations process

Biobutanol supporters claim significant advantages over other biofuels used to fuel internal combustion engine vehicles (ICEVs) and other liquid-fueled processes:

  • Butanol does not attack materials commonly used in vehicular internal combustion engines.
  • Biobutanol can also be used in the industrial paint and solvent industry to replace fossil butanol.

James Liao, a chemical engineer at the University of California, Los Angeles, developed a method to insert genes from Clostridium acetobutylicum which are responsible for production of butanol into the bacterium Escherichia coli. [1] [2]

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