Aristidou A, Penttilä M
VTT Biotechnology, PO Box 1500, VTT Espoo, 02044, Finland.
Curr Opin Biotechnol. 2000 Apr;11(2):187-98. doi: 10.1016/s0958-1669(00)00085-9.
Lignocellulosic materials containing cellulose, hemicellulose, and lignin are the most abundant renewable organic resource on earth. The utilization of renewable resources for energy and chemicals is expected to increase in the near future. The conversion of both cellulose (glucose) and hemicellulose (hexose and pentose) for the production of fuel ethanol is being studied intensively, with a view to developing a technically and economically viable bioprocess. Whereas the fermentation of glucose can be carried out efficiently, the bioconversion of the pentose fraction (xylose and arabinose, the main pentose sugars obtained on hydrolysis of hemicellulose), presents a challenge. A lot of attention has therefore been focused on genetically engineering strains that can efficiently utilize both glucose and pentoses, and convert them to useful compounds, such as ethanol. Metabolic strategies seek to generate efficient biocatalysts (bacteria and yeast) for the bioconversion of most hemicellulosic sugars to products that can be derived from the primary metabolism, such as ethanol. The metabolic engineering objectives so far have focused on higher yields, productivities and expanding the substrate and product spectra.
含有纤维素、半纤维素和木质素的木质纤维素材料是地球上最丰富的可再生有机资源。预计在不久的将来，可再生资源用于能源和化学品的利用将会增加。目前正在深入研究将纤维素（葡萄糖）和半纤维素（己糖和戊糖）转化用于生产燃料乙醇，以期开发出一种技术上和经济上可行的生物工艺。虽然葡萄糖的发酵可以高效进行，但戊糖部分（木糖和阿拉伯糖，半纤维素水解得到的主要戊糖）的生物转化却是一项挑战。因此，很多注意力都集中在能够有效利用葡萄糖和戊糖并将它们转化为有用化合物（如乙醇）的基因工程菌株上。代谢策略旨在生成高效生物催化剂（细菌和酵母），用于将大多数半纤维素糖生物转化为可从初级代谢衍生的产物，如乙醇。迄今为止，代谢工程的目标集中在提高产量、生产率以及扩大底物和产物谱。
