近日，中科院西双版纳热带植物园生物能源组的研究人员发现，高等真菌（主要是白色腐朽类）可在水解木材预处理过程中高效降解木质素，并对其工艺的技术整合、工程放大进行了论述和设计。这一成果可能有助于燃料乙醇的绿色高效生产。相关论文发表于国际期刊《生物燃料、生物产品和生物精炼》（Biofpr）。
纤维素水解后生成的葡萄糖是燃料乙醇和生物质冶炼工业最重要的原料。燃料乙醇目前被广泛用于替代石化汽油产品，但传统的发酵生产乙醇法要消耗大量粮食作物，引发粮食供应紧张和粮价上涨。
该研究组博士生田霄飞说，纤维素是地球上最为丰富的有机物之一，储量约占地球植物资源物质总量的33%，广泛存在于木材、秸秆、棉花等生物质中，常见的用于燃料乙醇制备的非粮作（植）物有工业大麻、柳枝稷、芒草、柳树、杨树等。目前，美国等国已开始探索用木质纤维素生物质和其他非粮作物为原料生产燃料乙醇。
但是，天然的木质纤维素被高度聚合的木质素包裹，这阻碍了纤维素与水解催化剂的接触，严重降低了反应效率。因此，在水解反应前，预处理是有效破坏木质素结构且膨化纤维素成分的必要步骤。
当前，常用于木质纤维素预处理的传统手段存在着不足之处，如物理法能耗高，化学法会污染环境，生物法效率低下，即使最有效的物理化学方法仍存在着设备要求较高、操作复杂等问题。近年来，廉价、高效、绿色的预处理技术受到全球学术界和工业界的关注。
研究表明，高等真菌，尤其是白色腐朽类，蕴藏着丰富的木质素氧化酶系，是自然界中高效降解木质素的生力军。该组的研究人员使用版纳植物园19种常见高等真菌的菌丝分离培养物处理柳树木材。初步研究发现，经7种真菌处理后的木材酶水解率有明显提高，且最大的提高了4.27倍。
以此为基础，田霄飞在导师方真研究员的指导下，概述和总结了应用白腐真菌预处理的技术原理和应用现状，并在该工艺的技术整合、过程优化、工程放大以及成本核算等方面进行了专门的论述与设计。他们的研究总结认为，白腐类真菌是一类在处理过程中具有良好应用前景的微生物。工业大规模使用白腐真菌，具有高通量、低成本的商业效益和绿色、低污染的环境效益，是常规预处理技术的一种补充或替代。
使用真菌处理生物质，在工业上成功的运用主要集中在蘑菇（食用菌）栽培料的预处理和造纸制浆脱色素领域；由于真菌生长缓慢，预处理周期太长，因此在木质纤维素预处理过程中尚未大规模应用，但前景可观。（生物谷Bioon.com）
doi:10.1002/bbb.346
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Impact and prospective of fungal pre‐ reatment of lignocellulosic biomass for enzymatic hydrolysis
Tian, Xiao‐fei; Fang, Zhen; Guo, Feng
The presence of lignin in lignocellulosic biomass leads to a protective barrier which prevents enzymes from being accessible to cellulose and hemicellulose for hydrolysis. As a result, pre-treatment is a ‘must’ step for subsequent enzymatic hydrolysis. Bio pre-treatment is normally conducted at low temperatures and low pressures without using expensive equipment, chemical agents, reactors, and additional energy for lignin removal and biomass structure destruction. Therefore, it is a green, safe, and inexpensive method. White-rot fungi (WRF), a group of fungi (more than 1500 different species) are successfully applied in bioconversion processes such as sewage treatment, biopulping, conversion of forest and agricultural residues to animal feeds, and the production of edible or medicinal mushrooms. In the bio pre-treatment process, WRF are mostly used for secreting ligninolytic enzymes, a variety of donor substrates and selective degradation of lignin. Current research related to WRF bio pre-treatment is mainly focusing on the following four aspects: (i) selection of candidate strains for certain biomass materials; (ii) optimization of cultivation methods; (iii) characterization of fungal treated materials; and (iv) evaluation of combining bio pre-treatment with chemical or physicochemical approaches. Future prospects and recommended research work on applying WRF in bio pre-treatment are also briefly introduced and summarized in this review. These include (i) integrated methods (i.e. co-treatment with organic solvents, diluted acids, supercritical CO2 and ionic liquids) to resolve problems existing in fungal pre-treatment applications; (ii) mutation breeding and crossbreeding of fungal mycelia to obtain engineering strains; and (iii) integration of fungal pre-treatment with simultaneous saccharification and fermentation to produce biofuels and value-added products.
