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Study of the effect of microbial degradation of lignin on its molecular weight
Fialová, Tereza ; Hudečková, Helena (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis deals with the microbial degradation of lignin using wood-degrading fungi Fomitopsis pinicola and Lenzites betulina. In the first phase of the experimental part, media screening was carried out, the aim of which was to select the best media for fungal growth and production of ligninolytic enzymes. Based on the determination of activity, in the next step, the conditions for their production were optimized in selected media. As part of these experiments, the optimal concentration of lignin and glucose was selected for subsequent cultivations. Commercially available lignin was used as substrate. Based on the results of measured enzyme activities, Lenzites betulina was selected as the better producer. The most produced enzyme of this fungus was laccase, followed by manganese-dependent peroxidase and the least lignin peroxidase. Further experiments were performed only with L. betulina. In the next part of the experiment, lignin was characterized, and its properties compared before and after microbial degradation. Its molecular weight was determined by SEC-MALS and the change in structure by FTIR. The molecular weight of lignin decreased after cultivation and a change in its structure was also noted. The results show that the microbial degradation of lignin was successful.
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Studium produkce lakázy vybranými druhy hub
Ovchynnikova, Oleksandra
The importance of lignin-degrading fungi and their ligninolytic enzymes has been well appreciated globally, because of their potential use in various industries. This bachelor thesis is focused on study of potential production of extracellular ligninolytic enzymes by brown rot fungi. In the literary review selected strains of brown rot fungi and its most studied ligninolytic enzymes are characterized. The use of laccase in various industries especially food industry are summarized. Activity of ligninolytic enzymes produced by brown rot fungi Laetiporus sulphureus, Serpula lacrymans, Gloeophyllum sepiarium, Phaeolus schweinitzii and Laetiporus montanus during submerged cultivation for 24 days was evaluated. Laccase, lignin peroxidase and manganese dependent peroxidase activities were measured spectrophotometrically. For all enzymes, the highest activity was observed on the 12 day. Selected fungi produced the most lignin peroxidase. Laetiporus sulphureus and Gloeophyllum sepiarium showed the highest values of enzyme activities. It has been found that the enzymatic activity of fungi depends on the geographical location and the specific habitat. Enzyme activities of the same strain taken from different locations were different.
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