The Solid State Fermentation Of Ferulic Acid Esterase And Its Application In The Pulping Process

This project has studied the screening technique for the strain producing ferulicacid esterase, the fermentation technology of producing enzyme, the separation andpurification process of the enzyme, the ferulic acid esterase compound preparation andits application in biological method dissolving pulp preparation process etc.Ferulic acid esterase (FAE,E.C.3.1.1.73), a biotechnologically important enzymeis responsible for the hydrolysis of the ester linkage present between3-methoxy4-hydroxy cinnamic acid (ferulic acid) and sugar and for their subsequent utilization asbioactive compounds. And this enzyme widely distributed in plants and microorganisms,part of them were purified and characterized. Ferulic acid ester hydrolysis phenolgroups which involved in the Arab xylan crosslinking of other polymer structure. It isvery important to break down the cell wall, making the glycosyl hydrolase are morelikely to be applied to raw material. FA released from plant cell wall by the action ofFAEs is an effective natural antioxidant with potential applications in thepharmaceutical and food industries. FAEs could be used in pulp and paper processingand as animal feed additives to facilitate nutrient assimilation.The paper reported the production of ferulic acid esterase (FAEs) produced bymicroorganism.and the application of FAEs in clean pulping.method A fungus strainwhich can release FAEs was isolated through the plate transparent zone method andshake flasks culture from laboratorypreservation strains and was identified as Aspergilluterreus. We optimized the fermentation medium and transformation condition of theselected Aspergillu terreus, and determined that the optimal cultivating substrates werebran mixed with a small amount of cottonseed hulls, the nitrogen sources fit for additionwere ammonium sulfate and urea. Inorganic salts used in the test was not expressedbetter results than the original medium salts through the single factor experiment andthe composite experiment. And then PB experiments was used to determine factorsaffecting the enzyme production medium and the final fomular.In order to get pure ferulic acid esterase, a series of methods of microfiltration,ultrafiltration, ammonium sulfate precipitation and so on were used for separation andpurification of leaching solution of solid state fermentation. After microfiltration andultrafiltration, the ferulic acid esterase enzyme activity of the concentrate was0.616U/ml, was2.04times that of the original crude enzyme liquid. After further purification with ammonium sulfate precipitation, the maximum enzyme activity was0.500U/mLwith yield of81.17%. Through the research on the character of ferulic acid esterase, welearned that the optimum pH (Tris HCl buffer) was8.5, with the stability range of4.0to9.0, and the optimum temperature was60℃with the temperature stability range of40to55℃.The dissolving pulp could reached the national first class standard after usingmultiple enzyme prepared with ferulic acid esterase, lipase and cellulase synergisticeffects on cotton linter for dissolving pulp preparation. The pretreatment condition withenzyme preparation on cotton linter was ferulic acid esterase0.5U/g and lipase0.1U/g,pH7.5, temperature55℃for24h. And then treated with cellulose50U/g at pH5.0,55℃for24h, defibering and beating and refining the relief pulp, added aqueoussolutions containing0.4%EDTA with pH of3to the pulp and mixed, chelatingtreatment under70℃for70min. Then the pulp mixed with13.5%NaOH,0.4%MgSO4and9%H2O2digesting within100℃for2.5h. The pulp was washed with water toneutral,and then treated with3%HCl aolution at temperature of60℃for70min thenwashed with water to neutral to get the dissolved pulp. Determined with the nationalstandard, all the parameters reached the national first class standard. The yield retio ofdissolving pulp was over86%, the α-cellulose content is more than95%, reactionproperty was less than20s, the ash content was under1%, the iron content was19mg/Kg or less, the alkali absorption value was between500and600. The aboveparameters are conform to the requirement of national standard.Combination of enzyme treatment and chemical method may be concluded the newpulping technology. Compared with traditional process, the technolog had theadvantages of reducing the chemical dosage, reducing the energy consumption,reducing the pollution load, and the advantages of higher yield and the stable quality.