Title :

Plant Cell-Wall Recalcitrance: A Key Scientific Challenge

Description :

The tough structural materials in plant cell walls form a complex composite exquisitely designed to support plant structure and resist biological and chemical assaults. This natural resistance to degradation is called “recalcitrance” and represents one of the greatest challenges to attaining a cost-effective cellulosic biofuel industry. A large portion of the plant cell wall contains long chains of sugars (polysaccharides) that can be converted to biofuels. Cellulose—the most abundant biological material on Earth—consists of tightly bound sugar chains organized into strong cable-like structures (microfibrils). Like steel girders stabilizing a skyscraper’s structure, microfibrils reinforce plant cell walls. Locked away within the microfibril’s sugar chains are thousands of glucose molecules, a type of six-carbon sugar readily converted into biofuels by microbes. Physically accessing these sugars, however, is difficult. Cellulose microfibrils are embedded within a matrix of other polymers (hemicellulose and lignin). Hemicellulose, a mix of branched polysaccharides made up of five- and six-carbon sugars, links to lignin, a rigid noncarbohydrate polymer that forms a protective coating to shield cellulose and hemicellulose from enzymatic attack. In addition to serving as a physical barrier to enzymes and microbes, lignin also is a source of chemical by-products that can inhibit sugar conversion to biofuels.

Citation :

Bioenergy Research Centers: An Overview of the Science, U.S. Department of Energy, February 2008. DOE/SC-0104.

Credit or Source :

Genome Management Information System, Oak Ridge National Laboratory

Medium Res :

Medium-Resolution Image

Hi Res :

High-Resolution Image