Study Breakdown: A White-Rot Fungus (Pleurotus pulmonarius) and PCDD/F-Contaminated Field Soil

Summary

Researchers in Taiwan mixed heavily contaminated soil from a closed pentachlorophenol plant with a white-rot fungus grown on solid material, and reported that 96% of the dioxins and furans (PCDD/Fs, measured as toxic equivalents) were gone after 72 days in a controlled incubator [1]. That is a strong result for lab-scale treatment of real, unsterilized field soil. It is also one study, of soil mixed with inoculum and treated outside the ground, from one site. It tells us nothing about any specific incident, about soil treated in place, or about any commercial product.

The paper

This summary draws on the published abstract and journal record. Funding and conflict-of-interest statements are in the full paper, which may require a subscription.

The question

The authors call PCDD/F biodegradation in unsterilized soil notoriously intractable. They asked whether a white-rot fungus, a group with enzymes that break down tough plant material, could treat PCDD/F-contaminated soil taken from a real site, with its native microbes intact.

What they did

• The unsterilized soil came from a long-closed pentachlorophenol plant in southern Taiwan, and its total PCDD/F was 14,000 plus or minus 2,400 ng I-TEQ per kg (I-TEQ, the International toxic equivalent, weights each congener by toxicity) [1].
• The treatment used Pleurotus pulmonarius, grown as solid fungal inoculum and mixed into the soil at a dry-weight ratio of 1 part soil to 1.4 parts inoculum, a method called solid-state fermentation [1].
• The soil was held at 26 plus or minus 2 degrees C in a controlled environment for 72 days [1].
• The team measured PCDD/F by congener group, along with the fungal enzymes laccase and manganese peroxidase over time [1].

What they found

The authors note the residual fell below a regulatory control limit of 1,000 ng I-TEQ/kg. Because low- and high-chlorinated congeners disappeared together, they describe the removal as nonspecific, and say the method overcame the usual intractability of PCDD/F degradation in unsterilized soil [1].

Study design

This was a controlled-environment treatment of real field soil, and it was never run as a field trial. It has real strengths: contaminated soil from an actual site, native microbes left in place, results by congener group, and a high starting level of 14,000 ng I-TEQ/kg, so 96% is a large absolute drop. The abstract doesn’t describe replication or a separate control arm, so check the full paper for those.

What it does not show

• The study doesn’t show treatment in place, because the soil was mixed with 1.4 times its dry weight in colonized fungal material and held at a controlled temperature. That ex situ process is far from spraying a lawn, field or yard.
• It doesn’t speak to any particular incident, because dioxin mixtures from different sources carry different congeners in different proportions, and a result from a pentachlorophenol plant doesn’t transfer to another source.
• It leaves toxicity beyond TEQ open, since whether breakdown products formed, and whether the soil is safe for a given use, are separate questions the abstract doesn’t answer.
• It says nothing about low concentrations, because the starting level was very high.
• It covers 72 days and leaves open how the soil behaves afterward.
• It shows nothing about Elm Dirt products, since Pleurotus pulmonarius is not among the species identified in our products’ lab analyses; more on the wider picture is in dioxins and furans in soil.

How it fits with other research

A review of aerobic and anaerobic routes notes that aerobic bacterial degradation of dioxins and furans is reported mainly for low-chlorinated congeners, and that anaerobic reductive dechlorination may be one of the few routes for the heavily chlorinated ones [2]. This study suggests a third route, in which the fungus appeared to work nonspecifically, removing low- and high-chlorinated congeners together, and the link to manganese peroxidase points to enzymes released outside the fungal cells [1]. Our post on white-rot fungi in soil remediation covers the group.

What would strengthen it

• Replication in other labs and other soils
• A trial treating soil in place instead of mixing it with inoculum
• Toxicity testing of the treated soil alongside TEQ
• Results at lower, more typical concentrations
• Follow-up beyond 72 days

Why a decision-maker might care

Biological treatment of dioxin-contaminated soil is an active research area, and a result like this justifies watching that research and possibly running a treatability test on soil at a similar concentration. It does not show biology can clear a dioxin site, and a regulator would expect a site-specific pilot first.

Further reading

• Dioxins and furans in soil, explained: TEQ, behavior in soil, and other biological routes.
• Dioxins and furans: the contaminant profile.
• How we use the research: what we cite and what we measure.

Glossary

• PCDD/F stands for polychlorinated dibenzo-p-dioxins and dibenzofurans, the “dioxins and furans.”
• I-TEQ is the International toxic equivalent, in which each congener’s concentration is multiplied by a toxicity factor and the results are added.
• Solid-state fermentation means growing a fungus on a solid material with little free water.
• White-rot fungi are fungi that break down lignin, the tough part of wood, using extracellular enzymes.
• A congener is one specific member of a chemical family.
• Non-sterilized soil is soil with its native microbes still present.

Open questions

Whether the result replicates, how the process would behave in another soil, and what a practical field version would cost are all unknown. If you are evaluating dioxin-impacted soil and want a study like this explained in plain language, get in touch.

Sources

All links checked 2026-10-01.

1. Kaewlaoyoong A, Cheng CY, Lin C, Chen JR, Huang WY, Sriprom P. White rot fungus Pleurotus pulmonarius enhanced bioremediation of highly PCDD/F-contaminated field soil via solid state fermentation. Science of the Total Environment 738:139670 (2020). doi:10.1016/j.scitotenv.2020.139670
2. Bunge M, Lechner U. Anaerobic reductive dehalogenation of polychlorinated dioxins. Applied Microbiology and Biotechnology 84:429 to 444 (2009). doi:10.1007/s00253-009-2084-7