Monday, November 19, 2007

Global Warming and shortage of fossile chemical feedstock

1st International Biorefinery Workshop U.S. DOE and EU, July, 20 and 21, 2005, Washington DC | Yeast-based bio-refineries | Bärbel Hahn-Hägerdal | Applied Microbiology, LTH/Lund University | P O Box 124, SE-221 00 LUND, Sweden | mbarbel.hahn-hagerdal at

Helge: Lund Technical Highschool, Lund, Sweden.

The prospects of global warming and the potential future shortage of fossil chemical feedstocks have turned the interest towards utilization of renewable raw materials derived from agriculture and forest products. Such raw materials – lignocellulosics – are composed of lignin, cellulose and hemicellulose.

Helge: Yes, We are looking into the same agricultural and forest products and feedstocks.

In a bio-refinery concept the raw material may be pre-treated at elevated temperatures with small amounts of dilute acid or SO2 to make cellulose and hemicellulose accessible to subsequent acid or enzymatic hydrolysis.

Helge: Yes.

During pre-treatment and acid hydrolysis fermentation inhibitors – phenol and furan derivatives and low molecular weight fatty acids - are released. Cellulose and hemicellulose are hydrolyzed to fermentable monomer sugars (glucose, mannose, galactose, xylose and arabinose), while lignin is recovered as a solid fuel.

Helge: Hydrolyzed to fermentable monomer sugars...

Hydrolyzed lignocellulosic raw materials thus comprise a mixed-sugar substrate in an inhibiting matrix. In this bio-refinery concept these substrates are converted to value-added products, such as alcohols, aldehydes, acids and esters.

Helge: Resulting in value-added products.

Because of its high inhibitor tolerance, its wide biological activity and its proven record as industrial fermentation microorganism, Baker’s yeast Saccharomyces cerevisiae is the prime choice of microorganism for a bio-refinery.

Helge: The micro-organism for a biorefinery.

The advent of modern DNA-technology including metabolic engineering, inverse metabolic engineering and evolutionary engineering as well as the concept of systems biology permits the development of yeasts with novel and artificial activities to be exploited in the pharmaceutical, food, feed and chemical industry.

Helge: We need to talk more about this.

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