Study on the Enzymatic Catalysis of Lignin for Product Aroma Compound

Author:Cui Jing Jing

Supervisor:chen bing hui lin lu


Degree Year:2017





Lignin is the main renewable aromatic compounds,is the second most abundant renewable natural organic matter on the earth.And it is a byproduct of the wood industry and paper industry.Due to the lack of effective use and it becoming environmental pollutants.Lignin has a unique phenylpropane structure unit,making it most probable to be the stable source of aromatic compounds in the future.In this paper,we use lignin-degrading enzymes and its mimics converse lignin and its model compounds to phenolic compounds in different degradation systems.Ⅰ.Get lignin peroxidase,manganese peroxidase and laccase by fermenting phanerochaete chrysosporium.We studied the reaction process by detect the changes of enzyme component and lignin structure in water solution.Lignin degradation requires multiple enzymes collaborative.Component in the enzyme solution is more important than the size of the enzyme activity.LiP has a higher activity than LiP/MnP/Lac,the two enzymes degrade alkali lignin in the same condition.The former degradation rate is 20.064%,the latter is 28.8362%.Analysis the content of phenol in the two reaction solutions.Complex enzyme is higher than single enzyme.Lignin degradation reaction was the radical reaction.Incorporation the stabilizer of radical in the reaction system can control the reaction in a particular stage,to produce amount of phenolic compounds.This paper selected two radical stabilizers--Formic acid and Methanol.To added the formic acid and methanol in reaction system,analysis of the weight loss of alkali lignin and phenol produced.The situation is methanol is conducive to weight loss alkali lignin,formic acid conducive to the accumulation of phenolic substances.Ⅱ.We selected three types of ionic liquid witch can dissolve the lignin at room temperature.[Bmim][MeSO4],[Mmim][MeSO4]&[Hmim][CF3SO3].Ionic liquid dissolved lignin by hydrogen bonding,Leads to mobility increased.When the lignin and water are present at the same time,the water-soluble ionic liquids form hydrogen bonds with water for priority.And the lignin precipitated.Water-insoluble ionic liquid dissolved lignin still not mutual solubility with water.Due to the anions CF3SO3,ionic liquid has to form a biphasic with water and phase converted abilities.According to the characteristics of ionic liquids,take different strategies to make it reaction in a homogeneous phase.Ⅲ.Ionic liquid that dissolved lignin can miscible with amyl alcohol.The complex lignin-ionic liquid mixed into the emulsifier of micro emulsion with amyl alcohol.Lignin degradation enzymes located in the aqueous phase.It reacted with lignin that binding on the limiting membrane in micro emulsion.The product extracted into the organic phase.These micro emulsion reactor reactions realized the extraction and reaction carried out at the same time.Ⅳ.[Hmim][CF3SO3]dissolved lignin,and the ability of the phase transition has not disappeared.It can used for ternary liquid-liquid equilibrium system.The reaction system was more suitable for degradation lignin or lignin model compounds by non-protease catalysts.For the cation Hmim cause protease inactivation.Ⅴ.Enzyme mimics(EDTA-Fe&GIF)has been synthesized.Evaluation of enzyme mimics degradation lignin model compounds DHPs in ternary liquid-liquid equilibrium system.The experimental results show that two types of enzyme mimics degradation DHPs efficient and accumulation of phenolic compounds.