近日，中科院西雙版納熱帶植物園生物能源組的研究人員發(fā)現(xiàn),，高等真菌（主要是白色腐朽類）可在水解木材預(yù)處理過程中高效降解木質(zhì)素,，并對(duì)其工藝的技術(shù)整合,、工程放大進(jìn)行了論述和設(shè)計(jì)。這一成果可能有助于燃料乙醇的綠色高效生產(chǎn),。相關(guān)論文發(fā)表于國際期刊《生物燃料,、生物產(chǎn)品和生物精煉》（Biofpr）。
纖維素水解后生成的葡萄糖是燃料乙醇和生物質(zhì)冶煉工業(yè)最重要的原料,。燃料乙醇目前被廣泛用于替代石化汽油產(chǎn)品,，但傳統(tǒng)的發(fā)酵生產(chǎn)乙醇法要消耗大量糧食作物，引發(fā)糧食供應(yīng)緊張和糧價(jià)上漲,。
該研究組博士生田霄飛說,，纖維素是地球上最為豐富的有機(jī)物之一，儲(chǔ)量約占地球植物資源物質(zhì)總量的33%,，廣泛存在于木材,、秸稈、棉花等生物質(zhì)中,，常見的用于燃料乙醇制備的非糧作（植）物有工業(yè)大麻,、柳枝稷、芒草,、柳樹,、楊樹等。目前,，美國等國已開始探索用木質(zhì)纖維素生物質(zhì)和其他非糧作物為原料生產(chǎn)燃料乙醇,。
但是，天然的木質(zhì)纖維素被高度聚合的木質(zhì)素包裹,，這阻礙了纖維素與水解催化劑的接觸,，嚴(yán)重降低了反應(yīng)效率。因此,，在水解反應(yīng)前,，預(yù)處理是有效破壞木質(zhì)素結(jié)構(gòu)且膨化纖維素成分的必要步驟。
當(dāng)前,，常用于木質(zhì)纖維素預(yù)處理的傳統(tǒng)手段存在著不足之處,，如物理法能耗高，化學(xué)法會(huì)污染環(huán)境,，生物法效率低下,，即使最有效的物理化學(xué)方法仍存在著設(shè)備要求較高,、操作復(fù)雜等問題,。近年來，廉價(jià),、高效,、綠色的預(yù)處理技術(shù)受到全球?qū)W術(shù)界和工業(yè)界的關(guān)注,。
研究表明，高等真菌,，尤其是白色腐朽類,，蘊(yùn)藏著豐富的木質(zhì)素氧化酶系，是自然界中高效降解木質(zhì)素的生力軍,。該組的研究人員使用版納植物園19種常見高等真菌的菌絲分離培養(yǎng)物處理柳樹木材,。初步研究發(fā)現(xiàn)，經(jīng)7種真菌處理后的木材酶水解率有明顯提高,，且最大的提高了4.27倍,。
以此為基礎(chǔ)，田霄飛在導(dǎo)師方真研究員的指導(dǎo)下,，概述和總結(jié)了應(yīng)用白腐真菌預(yù)處理的技術(shù)原理和應(yīng)用現(xiàn)狀,，并在該工藝的技術(shù)整合、過程優(yōu)化,、工程放大以及成本核算等方面進(jìn)行了專門的論述與設(shè)計(jì),。他們的研究總結(jié)認(rèn)為，白腐類真菌是一類在處理過程中具有良好應(yīng)用前景的微生物,。工業(yè)大規(guī)模使用白腐真菌,，具有高通量、低成本的商業(yè)效益和綠色,、低污染的環(huán)境效益,，是常規(guī)預(yù)處理技術(shù)的一種補(bǔ)充或替代。
使用真菌處理生物質(zhì),，在工業(yè)上成功的運(yùn)用主要集中在蘑菇（食用菌）栽培料的預(yù)處理和造紙制漿脫色素領(lǐng)域,；由于真菌生長緩慢，預(yù)處理周期太長,，因此在木質(zhì)纖維素預(yù)處理過程中尚未大規(guī)模應(yīng)用,，但前景可觀。（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.
