能源问题一直是现代社会的一个重要的问题，不过美国罗彻斯特 (Rochester)大学的研究人员，发表在最新一期美国国家科学院院刊 (PNAS)的一篇论文，揭露了该校的科学家，找到了微生物用来生产乙醇 (Ethanol)的酵素基因，将来很可能利用这种蛋白质酵素的作用，分解原本像是除草或是稻杆这类的废弃物，转换成干净清洁的能源。
据该校化学工程学系 David H. Wu教授表示，这次研究人员以可以分解大量生物质量 (biomass)的细菌为目标，深入的分析细菌酵素的活动，希望能够找到加速产生乙醇的方法，因为就过去的经验来说，细菌是可以透过分解代谢的方式，产生可以作为能源使用的乙醇，但这个转化的过程过于缓慢，特别是属于大质量废弃物的木质材料，质地非常的坚硬，不容易被酵素蛋白质所分解，其它像是玉米这类较软的材质，虽然可以较容易的转换成为酒精，但却拥有较高的经济价值，因此找出细菌到底用那一类酵素，透过怎样的过程来有效率的产生酒精，就成了研究人员首要的目标。
研究人员把目标，放在一种称为 C. thermocellum的细菌身上，因为就先前的了解，该细菌只利用一个步骤，就可以产生酒精，不过该细菌身上有多达 100多种的酵素，光凭排列组合，很难找出真正的作用者，研究人员仔细的分析，终于发现细菌会透过少量的特殊酵素，藉由产生一种称为 laminaribiose的糖类，来感应周遭大量纤维素的出现，因而启动称为 CelC和 LicA的木质分解酵素。
研究人员找到了这两个酵素蛋白质，就等于开了一扇大门，目前透过定序的过程，探究酒精代谢的关键，也许在未来，光凭腐蚀的树干，就可以获得推动汽车的燃料。
(资料来源 : Bio.com)
部分英文原文：
Published online before print February 27, 2007, 10.1073/pnas.0700087104
PNAS | March 6, 2007 | vol. 104 | no. 10 | 3747-3752
Induction of the celC operon of Clostridium thermocellum by laminaribiose
Michael Newcomb, Chun-Yu Chen, and J. H. David Wu*
Department of Chemical Engineering, University of Rochester, Rochester, NY 14627-0166
Communicated by Arnold L. Demain, Drew University, Madison, NJ, January 5, 2007 (received for review December 12, 2006)
Clostridium thermocellum is an anaerobic, thermophilic, cellulolytic, and ethanogenic bacterium. It produces an extracellular multiprotein complex termed the cellulosome, which consists of >70 subunits, most of them glycosyl hydrolases. It also produces many free glycosyl hydrolases. How the organism commands such a large number of genes and proteins for biomass degradation is an intriguing yet unresolved question. We identified glyR3, which is cotranscribed with the cellulase/hemicellulase genes celC and licA, as a potential cellulase transcription regulator. The gel-shift assay (EMSA) revealed that the recombinant GlyR3 bound specifically to the celC promoter region. GlyR3 was also identified from the lysate of the lichenan-grown cells, which bound to the same sequence. DNase I footprinting and competitive EMSA showed the binding site to be an 18-bp palindromic sequence with one mismatch. The DNA-binding activity was specifically inhibited by laminaribiose, a -1-3 linked glucose dimer, in a dose-dependent manner. In in vitro transcription analysis, celC expression was repressed by rGlyR3 in a dose-dependent manner. The repression was relieved by laminaribiose, also in a dose-dependent manner. These results indicate that GlyR3 is a negative regulator of the celC operon consisting of celC, glyR3, and licA, and inducible by laminaribiose. Thus, the bacterium may modulate the biosynthesis of its enzyme components to optimize its activity on an available biomass substrate, in this case, -1-3 glucan, because both CelC and LicA are active on the substrate. The results further indicate that, despite the insolubility of the biomass substrate, regulation of the degradative enzymes can be accomplished through soluble sugars generated by the action of the enzymes.
