Erika Winquist

Decolorization of simulated textile dye baths by crude laccases from Trametes hirsuta and Cerrena unicolor

In this study crude laccases from the white‐rot fungi Cerrena unicolor and Trametes hirsuta were tested for their ability to decolorize simulated textile dye baths. The dyes used were Remazol Brilliant Blue R (RBBR) (100 mg/L), Congo Red (12.5 mg/L), Lanaset Grey (75 mg/L) and Poly R‐478 (50 mg/L). The effect of redox mediators on dye decolorization by laccases was also assessed. C. unicolor laccase was able to decolorize all the dyes tested. It was especially effective towards Congo Red and RBBR with 91 and 80% of color removal in 19.5 h despite the fact that simulated textile dye baths were used. Also Poly R‐478 and Lanaset Grey were partially decolorized (69 and 48%, respectively). C. unicolor laccase did not need any mediators for removing the dyes. However, T. hirsuta laccase was only able to decolorize simulated Congo Red and RBBR dye baths (91 and 45%, respectively) in 19.5 h without mediators. When using mediators the decolorization capability was enhanced substantially, e.g. Poly R‐478 was decolorized by 78% in 25.5 h. On the whole, both laccases showed potential to be used in industrial applications.

Fungal enzyme production and biodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in contaminated sawmill soil

The current treatment method for PCDD/F-contaminated soil, which fulfils the requirements for POP soils, is incineration at high temperature. In this study, we investigated if bioaugmentation with fungal inoculum or treatment with manganese peroxidase (MnP) enzyme preparation could be used instead. The main source of PCDD/F contamination in Finland has been the national production and use of a chlorophenol containing wood preservative, which contained PCDD/Fs as impurities. Therefore, historically contaminated soils from three sawmill sites were used in the experiments. In bioaugmentation experiments with living fungal mycelia, enzyme production, CO2 production and degradation of chlorinated dioxins were measured. When cell free MnP preparation was added to the soil, it was likewise important to follow how enzyme activity was maintained in the soil. As a result of this study, we showed that fungi were able to efficiently degrade PCDD/F, but surprisingly the addition of MnP preparation did not have any effect to the PCDD/F concentration. However, substantial amounts of MnP activity were found in the soil still after 10d of incubation. Treatment with either Stropharia rugosoannulata or Phanerochaete velutina resulted in 62-64% decrease in WHO-TEQ value in 3months. One critical factor for efficient biodegradation was strong growth of fungal mycelia in non-sterile contaminated soil.