The Research Of The Oputimum Conditions And The Mechanism Of Penicillium Simplicissimum Biodegrading Rice Straw

Straw is the richest clean and renewable resource in the world, while the richand cheap resource cannot be used well and be largely wasted because of its scattereddistribution, big volume, high costs of collection and transportation, poor economy ofcomprehensive utilization. In recent years, biodegradation of straw has been paid moreand more attention by virtue of its low energy consumption, low cost, no pollution andso on. The biodegradation of straw by fungi is the hydrolysis and oxidation on fiberand lignin structure, which is mainly through cellulose, hemicellulase and ligninbiodegradation enzyme secreted by fungi, those enzymes can be used to measure thebiodegradation ability of fungi to straw. Penicillium simplicissimum was a kind offungus and was used to biodegrade rice straw and to research biodegradationmechanism to rice straw in this study. In order to better simulate biodegradationprocess of straw, straw was used as the sole carbon source, nitrogen source, with onlyMandel ’s inorganic nutrient solution for solid fermentation. After analyzed thechanges of cellulase, hemicellulase, lignin degradation enzyme, and the degradationeffect on fiber and lignin, we get that when Penicillium sp biodegraded rice straw, thebiodegradation of cellulose and hemicellulose were earlier than lignin, while theligninolytic enzymes lag behind the degradation effect of lignin. In order to achievethe optimum biodegradation conditions, the culture conditions of rice strawdegradation with Penicillium sp were studied in this paper by means of the threelevels-three factors orthogonal test, and we obtained that the optimal cultureconditions: temperature40℃, moisture content80%and pH8.We also researched the biodegradation mechanism of Penicillium sp on ricestraw through infrared spectrum analysis, Environmental Scanning ElectronMicroscopy analysis and eluent GC-MS analysis with rice straw biodegraded indifferent day in this paper. Through synthetic analysis base on these three detectionmethods, the basic process of rice straw biodegradated by Penicillium sp is that firstlysurface wax, cellulose and hemicellulose lignin are degraded, lignin,s side chains areoxidated and methylated; secondly the benzene rings are melted and then lignin isdegraded. Combined the analysis results together, we find that the degree of nudity ofthe silicon structure on the straw surface can be used as a characterization of thedegree of straw biodegradation. In addition, it has been proved in the research thatalkali lignin can induce Penicillium sp to improve the output of lignin biodegradation enzymes, and it has different induction effects on LiP, MnP and Lac respectively. Inthe contrast induction experiments with guaiacol, Tween80, we found that inductionof alkali lignin outperforms guaiacol and Tween80in proper concentration.