Study On Lignocellulose Biodegradation By Penicillium Simplicissimum And Its Mutants

Lignocellulose wastes come mainly from agriculture, wood hydrolysis industryand paper industry. They are polluting environment in many areas. Lignocellulose canhardly be biodegraded for it’s complex and stable structure. The way to biodegradeand utilize lignocellulose can be achieved only by changing its stable structure.Results by other researchers show that microbial species such as fungi, can secretlignocellulolytic enzymes which can biodegrade lignocellulose by breaking thechemical bonds of lignin. Penicillium simplicissimum (Oudem.) Thom BGA and itsmutants can secret lignocellulolytic enzymes as well as biodegrade lignocellulose.Therefore, this thesis is study on lignocellulose biodegradation by Penicilliumsimplicissimum and its Mutants.Firstly, Penicillium simplicissimum(Oudem.)Thom BGA can secretlignocellulolytic enzymes with high activities for hemicellulase, cellulase, ligninperoxidase(LiP), manganese peroxidase(MnP) and laccase(Lac). According to theresults and SPSS （Statistic Package for Social Science）, there is a great relationbetween those activity of lignocellulytic enzymes and the structure of lignocellulose.LiP and MnP can cause nonselective degradation of lignin, hemicellulose andcellulose, while degradation of lignin by Lac is selective. These enzymes always worksynergistically in the biodegradation process. In addition, the biosorption phenomenawas found in the process of liquid alkali lignin biodegraded by Penicilliumsimplicissimum, and it indicates that the biosorption plays an important role in thebiodegradation process of liquid alkali lignin.Secondly, the aim of this study was to obtain new Penicillium simplicissimummutants with high yield of ligninolytic enzymes. UV induced mutagenesis ofprotoplast was performed on original strain Penicillium simplicissimum (Oudem.)Thom BGA. Two genetically stable mutant strains J12and J18were selected from alarge amount of the regenerative mutants. The highest laccase and manganeseperoxidase (MnP) activities produced by strain J12was1.45and0.47-fold higher thanthat by original strain, reached44.0U/g and50.9U/g, respectively. The highestlignin peroxidase (LiP) activity of67.1U/g was obtained by strain J18, which is0.4-fold increased compared with its original strain. The highest biodegradation rateof lignin also was obtained by strain J18, which increased1.98-fold compared with its original strain. Further experiment confirmed that the activity of strain J12and strainJ18were stable and did not decrease generally after seven generations successivelypropagating.In summary, lignocellulose biodegraded by Penicillium simplicissimum is mainlycaused by the synergistic effect of lignocellulolytic enzymes. And the means ofmutagenesis of protoplast was an efficient method to enhance the ability oflignocellulose’s degradation.