Study On The Mechanism Of Lignin Degradation And The Biosorption Of Alkali Lignin By Penicillium Simplicissimum

Lignin is one of the major components of the cell wall of the plants, and its total content is only second to the cellulose in the world. It is mainly formed as the reticular structure around the cellulose, hemi cellulose to hardening the plant cell wall. Large numbers of studies have shown that, lignins has large molecular weight, poor solubility and contain a variety of biological stability of the complex chemical key type, what’s more, there exists no any repeat units or easy to hydrolysis of chemical bonds, that’s difficult for lignin to combine with microorganisms and extracellular enzyme. So it is a barrier to the carbon cycle in the earth’s biosphere, it is also the bottleneck of reusing the agriculturial and industrial wastes which contain lignin. Breaking the bondage would be the key of the key for us to use this kind of pontential renewable energy. Many reports showed that there is a kind of microorganisms in nature which can secrete specific enzymes to fracture the lignin into pieces by oxidation its partial chemical bonds. This paper mainly studies the mechanism of the biodegradation and adsorption of lignin by Penicillium simplicissimum.The lignin in this biodegradation research was extracted from poplar using organic solvent which could mainly maintain its natural attributes; it can avoid other impurities interferencing the final analysis. We researched the biodegradation mechanism of Penicillium simplicissimum through Fourier transform infrared spectrum analysis, differential calorimeter scans analysis and enzyme activity of ultraviolet spectrophotometric analysis. Through synthetic analysis that based on three detection methods we can know the degradation process by Penicillium simplicissimum. The process including oxidations, demethylations and aromatic ring splitting into small pieces that catalyzed by the ligninolytic extracellular enzymes. The color and other microscopic changes of the samples at different degradation time observed by microscope can be used as a token for the degree of lignin degradation; through the enzyme activity analysis we found that H2O2play a key role in lignin degradation by starting Lip and Mnp. Moreover, through the treatment of wastewater contained alkali lignin by Penicillium simplicissimum we can find that the removal of alkali lignin is mainly caused by adsorption of mycelium pellet, then the ligninolytic enzymes play a role in degradation. Fitting the result of the adsorption we find that it is more in line with the Langmuir model, the degree of fitting R2is0.995; and the maximum adsorption is30.3mg/g measured by saturated adsorption experiments. The last chapter of this paper tried to use the method of protoplast fusion to transfer Phanerochaete chrysosporium’s advantage in secreting high activity of Lip to Penicillium simplicissimum, hope to improve the mycelium’s ability of secreting ligninolytic enzymes and the ability in lignin degradation. Through enzyme activity measurement experiment, we can find that the activity of Lip and Lac has improved19.6%and25.7%, respectly, while the activity of Mnp basically remained unchanged. The alkali lignin removal rate increased by5%compared with the original Penicillium simplicissimum strain.