Application of ABE Fermentation

The ABE fermentation is an important industrial biotechnological process in which carbohydrate-based feedstocks are readily converted into acetone and butanol by solventogenic clostridia under anaerobic conditions. 

acetone and butanol are used as solvents and chemical building blocks for a diverse range of applications from paints, adhesives, and inks to food ingredients, cosmetic and personal care applications, to pharmaceuticals, plastics, and polymers. According to ICIS market data, the annual global markets for butanol is 3.4 million tonnes (worth over 5 billion) and for acetone it is 6 million tonnes (worth 6 billion). Today, the solvent markets are supplied petroleum-derived acetone and butanol. There is increasing demand for renewable chemicals derived from sustainable feedstocks as replacements for chemicals derived from oil. At present, renewable chemicals comprise about 10% of the chemical market and this is forecast to grow at 18% per year to 98.5 billion by 2020 [176]. 

Biobutanol is also an attractive biofuel with superior fuel properties but this application has not yet been established in the market. Biobutanol fits the existing fuel infrastructure it has a higher energy density (similar to petrol/gasoline) and better performance than bioethanol. In addition, butanol can be dehydrated to 1-butene and catalyzed into longer-chain oligomers for jet-fuel applications. Biobutanol can substitute for both ethanol and biodiesel in the biofuel market estimated to be 247 billion by 2020 [177]. 

The ABE fermentation process was first developed by C. Weizmann at Manchester University in 1912. Commercial production quickly spread to the United States and then worldwide during the First and Second World Wars first to produce acetone for ammunitions and then later to produce butanol for paint lacquers. The fermentation process fell out of favor in the United States and Europe in the 1950s when renewable solvents could no longer compete with their synthetic equivalents on price. Some production, via fermentation, continued in China, Russia, and South Africa until the early 1980s [54]. 

For example, an ABE plant was established at Germinston, South Africa in 1937 and ran successfully until 1983, first producing solvent from starch but switching to molasses. The fermentation and distillation recovery process operated in batch mode. The fermentation produced approximately 20gl of mixed solvents from 55 to 60 g 1 of substrate with solvent yields of about 0.35 g g sugar. The butanol acetone molar ratio is typically 2 1 [178]. 

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Regulation of Solvent Formation in C. acetobutylicum 345 Genetic Tools for Clostridial Species 346 Industrial Application of ABE Fermentation 353 Acknowledgments 355 References 355... 

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