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Production And Application Of The Laccase From Coriolus Versicolor

Posted on:2008-04-25Degree:DoctorType:Dissertation
Country:ChinaCandidate:E L GaoFull Text:PDF
GTID:1101360242995553Subject:Biochemical Engineering
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Laccase is one of multifunctional oxidoreductases,which has wide industrial application potential.In this dissertation,the production,catalytic characteristics of the laccase from Coriolus versicolor and its application in biofishing of blue jeans were investigated.The results were as follows:Laccase production by Coriolus versicolor in submerged fermentation was investigated.It was found that corncob residue,a lignocellulosic waste from xylose manufactory,could be used as carbon source for laccase production and its suitable concentration was 20.00 g/L.Additional glucose at prophase could promote the growth of mycelium and enhance the laccase production at anaphase,and the suitable glucose concentration was 10.00 g/L.C/N ratio was of great importance to the laccase production by Coriolus versicolor in submerged fermentation,and the appropriate C/N ratio was 20.In addition,ions such as Fe3+,Zn2+and Mn2+had an inhibitory effect on laccase production,while Cu2+was an effective enhancer during the submerged fermentation. Notablely,ascorbic acid could enhance the laccase production greatly.When 1.50mmol/L ascorbic acid was added to the medium,the laccase activity of fermentation broth reached 5170.80 IU/mL,which was 1.58 times higher than that of the control(no ascorbic acid was added).Aeration and agitation speed were very important during the laccase production in a 3.7L fermentor,and the laccase activity could reach 4948.40 IU/mL for 144 h when agitation speed and aeration rate were 300 r/min and 0.75 vvm,respectively.Laccase production from the mycelial pellets of Coriolus versicolor was carried out in a fluidized-bed bioreactor in consecutive batch fermentation,and the fermentation parameters were optimized.The suitable diameter of mycelial pellets diameter,aeration rate and the ratio of mycelial pellets to fermentation broth were 3 mm,0.10vvm and 15%,respectively.Phenol was an effective enhancer of laccase production,and the laccase activity was 2.10 times higher when 100mg/L phenol was added.The average laccase yield of consecutive batches(eight batches,20 d)reached 2.32×104 IU/L·h-1 under optimized conditions,which showed a good application potential in laccase production.The solid state fermentation process for laccase production was investigated using Coriolus versicolor.It was found that the laccase yield was much higher when using corn husk as partial carbon source compared with other cellulosic materials such as sawdust,bagasse,corncob residue,and so on.The maximal laccase activity reached 1.51×105 IU/g for 10 d when the ratio of the concentration of corn husk to bran was 6:4 and the water content of medium,inoculation volume,fermentation temperature were 65%,10%and 30℃,respectively.Catalytic characteristics of the laccase from Coriolus versicolor were investigated.The laccase was stable within the range of pH 5.0~6.0 and at the temperature lower than 40℃with the maximal activity at 55℃,pH 4.5.Using ABTS as substrate,the kinetic parameters,Km and Vmax,were 0.013 mmol/L and 948.0 mmol/L·min-1,respectively.Cu2+was a good laccase activity enhancer,while Na2SO4 was an enhancer of storage stability.The decolorization rate reached 96.5%with HBT as introducer for 40 min at temperature 50℃,pH value 4.5,indigo blue concentration 100mg/L,HBT concentration 0.1%and laccase dosage 100 IU.The result demonstrated that the laccase from Coriolus versicolor had a good promise in the biofishing of blue jeans and the decolorization of indigo blue dyeing wastewater.Acid cellulase has a good effect on the dehairing and decolorization of blue jeans during the biofinishing,but there is a high indigo-backstaining.In the presence of laccase,the degree of backstaining could be greatly decreased.When 5.0g/kg laccase was added,the indigo-backstaining degree of blue jeans could be reduced 83%after synergistic washed for 60 min,and the synergistic washing time could be shortened (only 30 min needed)and the amount of laccase could be decreased(only 2.5 g/kg needed)when laccase and acid cellulase were added solely.The synergism of laccase and acid cellulase not only reduced the backstaining and improved the quality of blue jeans consequently,but also reduced the amount of indigo blue in wastewater,which was of great benefit to alleviating environment pollution.The characteristics and innovations in this dissertation were obvious in the aspects such as production of the laccase from the mycelial pellets of Coriolus versicolor in a fluidized-bed bioreactor,catalytic characteristics of laccase,the synergism of laccase and acid cellulase during the biofinishing of blue jeans and the decolorization of indigo blue dyeing wastewater,and so on.The results were of meaningful value both in academic research and in practical applications.
Keywords/Search Tags:Laccase, Coriolus versicolor, Submerged fermentation, Lignocellulosic wastes, Fluidized-bed bioreactor, Immobilized laccase, Indigo blue, Decolonzation, Laccase-mediator system, Blue jeans, Backstaining, Biofinishing
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