Lynd Lee R, Weimer Paul J, van Zyl Willem H, Pretorius Isak S
Chemical and Biochemical Engineering, Thayer School of Engineering and Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA.
Microbiol Mol Biol Rev. 2002 Sep;66(3):506-77, table of contents. doi: 10.1128/MMBR.66.3.506-577.2002.
Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for "consolidated bioprocessing" (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.
我们依次从更高层次的聚合角度来研究微生物利用纤维素的基本特征，这些层次包括纤维素生物质的结构和组成、分类多样性、纤维素酶系统、纤维素酶的分子生物学、纤维素分解微生物的生理学、纤维素酶降解群落的生态学方面以及自然界中的限速因素。研究微生物利用纤维素的方法学基础，涉及在固体底物存在的情况下对细胞和酶进行定量分析，以及用于纤维素培养连续培养物的仪器和分析方法。纤维素水解的定量描述涉及纤维素酶的吸附、酶促水解速率、微生物利用纤维素的生物能量学、微生物利用纤维素的动力学，以及与可溶性底物动力学相比的对比特征。我们提出了关于处理纤维素生物质的生物学观点，包括预处理底物的特征和替代工艺配置。我们考虑了“整合生物加工”（CBP）中的生物发展，即在一步中实现纤维素分解酶的产生、生物质的水解以及将所得糖发酵为所需产品。我们研究了CBP的两种生物发展策略：（i）提高能够利用纤维素的微生物的产物产量和耐受性，或（ii）在具有高产物产量和耐受性的微生物中表达用于纤维素水解和利用的异源系统。最后的讨论确定了与微生物利用纤维素相关的未解决问题，提出了解决这些问题的方法，并在基础和应用背景下，将以微生物为导向的纤维素水解范式与更传统的以酶为导向的范式进行了对比。
