New Strategy to Enhance the Efficiency of Cereal Straw for Biofuel Production

(Phys.Org/University of Hong Kong) Straw is commonly used for feeding animals, burning, baling, etc. As one of the "Three Canton Treasures", straw can actually be used as a raw material to produce biofuel.

With an increasing demand on biofuel in recent years, cellulose from non-edible plant materials (e.g. sugarcane leaves, corn stalks, rice straw) has been used as raw materials for bioethanol production. However, since cellulose is crosslinked with lignin in plant cell walls, it is very difficult to release glucose from cellulose.

A collaborative research effort by the University of Hong Kong (HKU) and Kyoto University (Kyoto U) has revealed a new strategy to allow cellulose in rice straw to release its fermentable sugar more efficiently. The research breakthrough was recently published in a notable plant science journal Plant Physiology.

Rice and other cereals belong to the grass family (Poaceae). Lignin in their stems and leaves contain a special component called tricin. HKU plant biochemists Dr Clive Lo Sze-chung and his student Dr Lydia Lam Pui-ying, together with Kyoto U lignin specialist Dr Yuki Tobimatsu, started a collaborative project two years ago. According to their discovery, when flavone synthase II (FNSII), a key enzyme involved in tricin synthesis, is knocked out, not only is tricin not produced, but the lignin content in rice straw was also reduced by approximately one-third. In addition, the yield of glucose from cellulose degradation was increased by 37% without any chemical treatment.

Glucose released from cellulose can be used for bioethanol production. In other words, it is more efficient to produce ethanol from this kind of rice straw: the cost of lignin treatment can be reduced and the production of ethanol can be enhanced.

As plants in the grass family all contain tricin-bound lignin, this strategy can be applied to other cereals like maize, wheat, and barley as well as grass species (e.g. sorghum and switchgrass) cultivated around the world exclusively for ethanol production, so that they can be utilized more efficiently as raw materials for biofuel. READ MORE and MORE (Biofuels International) Abstract1 Abstract2 (Plant Physiology)