Unlocking the biodegradative potential of native white-rot fungi: a comparative study of fiberbank organic pollutant mycoremediation

Abstract

Fiberbanks refer to a type of fibrous sediment originated by the forestry and wood pulping industry in Sweden. These anthropogenic sediments are significantly contaminated with potentially toxic elements, and a diverse array of organic pollutants. Additionally, these sediments are of environmental concern due to their potential role in greenhouse gas emissions. Given the environmental risks posed by these sediments, the development of effective remediation strategies is of critical importance. However, no specialized methods have been established yet for the cleanup of this specific type of contaminated sediments. To identify effective fungal species for the mycoremediation of the fiberbank substrate, we performed a detailed screening experiment. In this research, we primarily aimed at assessing both the growth capacity and the proficiency in degrading organic pollutants of 26 native white-rot fungi (WRF) species. These species were sourced from natural forest environments in northern Sweden. The experimental setup involved evaluating the WRF on plates containing fiberbank material with a central Hagem-agar disc to closely monitor the interaction of these species with fiberbank substrates. Among the fungi tested, Laetiporus sulphureus exhibited the highest growth area percentage at 72%, followed by Hymenochaete tabacina at 68% and Diplomitoporus crustulinus at 67%. For the removal of 2-3 ring polycyclic aromatic hydrocarbons (PAHs), Phellinus punctatus led with 68%, with Cystostereum muraii at 57% and Diplomitoporus crustulinus at 49%. Regarding the removal percentage of 4-6 ring PAHs, Diplomitoporus crustulinus showed the highest efficiency at 44%, followed by Phlebia tremellosa at 40% and Phlebiopsis gigantea at 28%.

Keywords: Bioremediation; diplomitoporus crustulinus; fiberbank; mycoremediation; organic pollutants; phlebia tremellosa; phlebiopsis gigantea; white-rot fungi.

Figure 1.

The designated site for fiberbanks sampling is located within Sundsvall Bay, strategically positioned along the coastline of the Bothnian Sea in Sweden. This specific area, employed for mycoremediation experimental studies, is distinctly identified by a red square on the geographical mapping. (source: Google earth, https://earth.google.com/web).

Figure 2.

The experimental setup is illustrated through two distinct configurations as depicted in the accompanying images. Image (a) highlights the control samples, containing a layer of perlite with a central section of Hagem agar. Above this agar, centrally positioned, is a disc of fungal mycelium. In contrast, image (b) presents the treatments setup where perlite is replaced by fiberbanks material yet retains the same configuration of the centrally placed hagem-agar and the fungal mycelium disc positioned at the center and top of the agar. (photos: Burcu Hacıoğlu).

Figure 3.

After two months of growth (a) P. tremellosa, (b) P. gigantea, (c) D. crustulinus. (photos: Burcu Hacıoğlu).

Figure 4.

Removal percentage of 2–3 rings PAHs by WRF with standard deviation. (*) the letters indicate the outcomes derived from the post-hoc LSD test.

Figure 5.

The removal percentage of 4–6 ring PAHs, with standard deviation, by WRF is represented in a color-coded format. Green indicates a positive removal effect, where the concentration of 4–6 ring PAHs post-treatment by the fungi is lower than the initial concentration. Conversely, red signifies an increase, indicating that the concentration of 4–6 ring PAHs post-treatment is higher than the initial concentration. This color coding distinguishes between the efficacy of different fungi species in reducing (as desired) or increasing the concentration of these specific PAHs. (*) the letters indicate the outcomes derived from the post-hoc LSD test.