【作者】 宋安东；

【导师】 张百良；

【作者基本信息】 河南农业大学 ， 农业生物环境与能源工程， 2004， 博士

【摘要】 在我国能源安全问题日益突出、传统化石能源的消耗造成严重环境危害的形势下，在我国生物质尤其是秸秆造成了环境污染和秸秆资源的低水平利用的社会背景下，利用生物质(秸秆)纤维为原料来生产燃料乙醇成为一项迫切的、具有重要战略意义的任务。 国内外对生物质燃料乙醇进行了100多年的生产、应用和推广工作，但至今依然存在着许多关键的制约因素。研究表明，严重制约着生物质燃料乙醇规模化生产的关键瓶颈问题有两个：一是原料的预处理造成严重的环境污染或处理成本偏高；二是发酵阶段中糖的利用率低造成燃料乙醇产率偏低。作者认为采用生物降解原料中木质素的预处理工艺和采用戊糖发酵的微生物菌种来同步发酵糖化醪液中戊糖和己糖的工艺是解决生物质(秸秆)纤维燃料乙醇生产的重要途径。为此，本文通过大量的试验，取得了阶段性的结论或成果，该成果将对我国生物质(秸秆)纤维燃料乙醇的生产起到有力的推动作用。这些工作及成果主要包括以下几个方面： (1)固态培养降解木质素的工艺和机理试验研究。通过对固态培养降解条件和工艺研究，同时分析降解过程中微生物产木质纤维素酶类以及秸秆中主要组成的变化，结果表明在最佳的降解工艺和条件下，经过32d固态培养，木质素的降解率为62.551％。同时对生物降解木质素机理的研究表明，木质纤维素酶类的活力高低直接影响着秸秆中纤维素、半纤维素和木质素的降解，酶活力越高，降解率越大；纤维素和半纤维素的降解优先于木质素的降解；经生物降解后，木质素的结构发生了明显的变化。 (2)木质素降解酶降解木质素条件和机理试验研究。通过木质素降解酶降解木质素条件中温度、pH、酶量、降解时间等研究，表明在45℃、pH4.5、2ml酶液(粗过氧化物酶和粗漆酶各1ml)、72h的条件下，木质素的降解率为27.72％。试验中发现经过粗过氧化物酶和粗漆酶降解的秸秆木河南农业大学博士学位论文摘要质素发生了结构上的改变。 (3)木质素的降解对秸秆糖化的影响试验研究。为了研究木质素生物降解对秸秆糖化的影响，采用纤维素酶和木聚糖酶对秸秆进行双酶糖化的最佳条件，对9种经不同生物降解的秸秆样品的糖化率进行了对比研究，结果表明，木质素的降解可以显著提高秸秆的糖化率。 (4)戊糖发酵菌种的对比研究。通过对3个菌株平板培养和戊糖发酵试验，表明嗜靴管囊酵母P一01是优良的戊糖发酵菌株。 (5)戊糖和己糖同步发酵生产燃料乙醇条件试验研究。通过对戊糖和己糖混合液同步发酵产燃料乙醇中发酵温度、pH、摇床转速、接种量、发酵初始糖浓度、己糖与戊糖比例等条件的研究，获得了戊糖和己糖同步发酵生产燃料乙醇的最佳条件，该条件下糖醇转化率为35%。 (6) BPSS&CF秸秆纤维燃料乙醇生产工艺及技术经济分析。对以生物质(秸秆)纤维为原料，燃料乙醇生产采用BPsS&CF一理和BPSS&CF一6的工艺试验表明，燃料乙醇的产率分别为10，280/0和7.3lryo，对工艺的技术经济学分析表明，以生物质(秸秆)纤维为原料来采用生产燃料乙醇的技术是可行的，社会效益、环境效益和经济效益是显著的。 (7)漆酶目的基因的克隆和验证。通过RT一PCR技术，从香菇241中获得了大小为12lbp的目的漆酶laCI基因片段，该片段与GENEBANK中其他香菇的漆酶基因具有较高的同源性。更多还原

【Abstract】 Energy Safty Problem in China is becoming more and more outstanding day after day.Environmental pollution caused by traditional fossil energy consumption is more and more serious.Environmental pollution caused by biomass,especially straw,and the utilization of straw resource at low level in our country are asked to be solved as soon as possible. Converting biomass (straw) materials to fuel ethanol is being an urgent and significant strategic mission under these conditions and society backgrounds.Production,application and extension along with many others of fuel ethanol have been made over 100 years.However,there are many key obstacle factors especially two sides in it today.One is serious environmental pollution and high cost caused by pretreatment of materials,the other is the lower conversional rate of fuel ethanol during sugar fermentation.I think these problems can be solved through two ways.The first is to adopt lignin biodegradation technics in the process of materials pretreatment.The second is to co-ferment pentose and hexose during ethanol fermentation.Accordingly,lots of experiment have been done and period-conclusion have been made in this paper.Maybe the research results can strongly promote fuel ethanol production from biomass (straw) cellulose in our country.(l)Screening microbe of high activity of lignolytic enzyme and pentose-fermentation.An excellent lignin-biodegradation strain Guangcao (Volvariella volvacea) was obtained from 66 microbe strains through plate screening and liquid-fermentation experiment.P-01 (Pachysolen tannophilus) was proved to be an excellent pentose-fermentation strain by the contrast of 3 strains through plate culturation andpentose-fermentation experiments.(2)Experimental studies on technics and mechanism of lignin biodegradation through solid culturation.Experiments on the conditions and technics of lignin biodegradation during solid culturation were studied,meanwhile the activities of lignocellulostic enzymes secreted by microbe and the content variations of main composition in straw were analysed.The results show,after 32 days solid-culturation,62.551% lignin could be biodegradated under the optimal biodegradation technics and conditions.Studies on the mechnism of biodegradation indicate,that it is the lignocullolostic emzyme that has crucial effect on biodegradation of lignin,cellulose and hemicellulose,the higher enzymatic activities,the higher biodegradation rate of the compositions of straw.Biodegradation of cellulose and hemicellulose are significantly prior to the biodegradation of lignin.At the same time,lignin structure has also changed obviously after biodegradation.(3) Experimental studies on the conditions and mechanism of lignin biodegradation by lignolytic enzymes.Experiments on lignin biodegradation by lignolytic enzymes were studied under the conditions such as temperature,pH,enzyme amounts and biodegradation time.The results show that,after 72 hours,27.72% lignin was biodegradated under the conditions of 45℃,pH4.5,2ml enzyme(crude peroxidases and laccase 1ml respectively).It is also found that lignin structure has also changed obviously after biodegradation with crude peroxidases and laccase.(4)Experimental studies on the effect of straw saccharification by the lignin biodegradation.After the studies on the conditions of straw saccharification with cellulase and xylanase simultaneously,we compared among the saccharification rates of 9 kinds of straw which have been pretreated through different biodegradation ways.As a result,lignin biodegradation can improve the saccharification rate of straw outstandingly.(5)Experimental studies on pentose and hexose co-fermentation conditions for fuel ethanol.The optimal conditions of pentose and hexose co-fermentation to fuel ethanol was obtained after the experiments on temperature,pH,rotation speed,inoculation amounts,theinitial sugar concentration,the ratio of glucose to xylose.The results show that, the rate of sugar conversion to fuel ethanol is 35% under the optimal ferm更多还原