| 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...
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