Pharmaceutical degradation by white rot fungus Fomes fomentarius and its enzymes
Pelpolage, Lakma (2026)
Diplomityö
2026
School of Engineering Science, Kemiantekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe20260624102310
https://urn.fi/URN:NBN:fi-fe20260624102310
Tiivistelmä
The increasing occurrence of pharmaceutical residues in aquatic settings has increased awareness of the use of white-rot fungi and their extracellular enzymes for contaminant removal. Therefore, this study investigated ligninolytic enzyme production by Fomes fomentarius cultivated on sunflower seed shells under semi-solid-state fermentation (SSF) conditions and evaluated the degradation of venlafaxine (VFX) and tetracycline (TC) using fungal-derived laccase.
Laccase was identified as the main ligninolytic enzyme synthesized by F. fomentarius, whereas lignin peroxidase and manganese peroxidase activities were not observed. Maximum laccase activity reached 10,848 U/L on the 13th cultivation day with 1.5 mM copper sulphate, and the presence of VFX did not noticeably affect enzyme production. Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis showed a protein band at approximately 66 kDa, consistent with fungal laccases.
Enzymatic degradation experiments showed that the laccase–1-Hydroxybenzotriazole (HBT) system transformed VFX, achieving a maximum removal of 68.7% after 300 min. However, enzyme activity decreased considerably during the reaction. In the SSF system, increasing VFX-equivalent concentrations were observed despite sustained laccase activity,suggesting possible matrix-related interferences. Similar behavior was observed during TC degradation. In the presence of HBT, maximum TC removals of approximately 68% and 53% were achieved using starting laccase activities of 500 and 1000 U/L, respectively, although enzyme activity decreased markedly over time. ATR-FTIR analysis showed structural changes in both pharmaceuticals after treatment, indicating their transformation through oxidative reactions.
Phytotoxicity tests using Lactuca sativa showed that seed germination was not affected by either VFX or its degradation products. However, compared with the control, root elongation decreased by 20% in the VFX treatment and was completely inhibited by the degradation products, resulting in germination indices of 80% and 0%, respectively.
Overall, the results indicate that laccase produced by F. fomentarius has considerable potential for the transformation of pharmaceutical contaminants, particularly with HBT. However, the noticeable enzyme activity reduction and the increased phytotoxicity associated with the degradation products suggest that further studies are needed before fungal-based treatment systems can be applied in practice.
Laccase was identified as the main ligninolytic enzyme synthesized by F. fomentarius, whereas lignin peroxidase and manganese peroxidase activities were not observed. Maximum laccase activity reached 10,848 U/L on the 13th cultivation day with 1.5 mM copper sulphate, and the presence of VFX did not noticeably affect enzyme production. Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis showed a protein band at approximately 66 kDa, consistent with fungal laccases.
Enzymatic degradation experiments showed that the laccase–1-Hydroxybenzotriazole (HBT) system transformed VFX, achieving a maximum removal of 68.7% after 300 min. However, enzyme activity decreased considerably during the reaction. In the SSF system, increasing VFX-equivalent concentrations were observed despite sustained laccase activity,suggesting possible matrix-related interferences. Similar behavior was observed during TC degradation. In the presence of HBT, maximum TC removals of approximately 68% and 53% were achieved using starting laccase activities of 500 and 1000 U/L, respectively, although enzyme activity decreased markedly over time. ATR-FTIR analysis showed structural changes in both pharmaceuticals after treatment, indicating their transformation through oxidative reactions.
Phytotoxicity tests using Lactuca sativa showed that seed germination was not affected by either VFX or its degradation products. However, compared with the control, root elongation decreased by 20% in the VFX treatment and was completely inhibited by the degradation products, resulting in germination indices of 80% and 0%, respectively.
Overall, the results indicate that laccase produced by F. fomentarius has considerable potential for the transformation of pharmaceutical contaminants, particularly with HBT. However, the noticeable enzyme activity reduction and the increased phytotoxicity associated with the degradation products suggest that further studies are needed before fungal-based treatment systems can be applied in practice.