Fungus, white rot

Irpex lacteus (Fr.) Fr.

Milk-white toothed polypore

A white-rot fungus studied mainly in Prague for its resistance to pollutant toxicity and its ability to colonise soil. In direct comparisons on real soils it degrades PAHs and PCBs, but generally less than Pleurotus ostreatus.

Otto Miettinen, CC BY-SA 3.0

How it works

Mechanisms: mycodegradation
Enzymes: manganese peroxidase

Contaminants

Contaminant	Evidence	What was shown
Polycyclic aromatic hydrocarbons	laboratory	Two industrial soils, 14 weeks: removal of fluorene 41 and 67%, phenanthrene 20 and 56%, anthracene 29 and 49%, fluoranthene 29 and 57%, pyrene 24 and 42%, chrysene 16 and 32%, benzo[a]anthracene 13 and 20%, with lower ecotoxicity (Vibrio fischeri, mustard germination). Bhatt, Cajthaml & Šašek (2002) Mycoremediation of PAH-contaminated soil. Folia Microbiol 47:255-258, 2002
Creosote	laboratory	Soil from a wood-preserving plant (50-200 mg/kg PAH), 120 days at 15 °C: 27-36% PAH removal (47-59% of 2-ring, 9-14% of 4-ring, 11-13% of 5-6-ring), against 55-67% for P. ostreatus. In a 56-day bench test on soil from a West Virginia site the two fungi gave similar results, up to 67.3% of total PAHs. Byss et al. (2008) Fungal bioremediation of the creosote-contaminated soil. Chemosphere 73:1518-1523, 2008 Lamar, White & Ashley (2002) Evaluation of white-rot fungi for the remediation of creosote-contaminated soil. Remediation Journal 12:97-106, 2002
Polychlorinated biphenyls	laboratory	Long-term PCB-contaminated dumpsite soils, 12 weeks: the fungus oxidised and cleaved the PCB ring (hydroxylated and methoxylated PCBs and chlorobenzoates were found), but the best results were those of P. ostreatus. Stella et al. (2017) Bioremediation of long-term PCB-contaminated soil by white-rot fungi. J Hazard Mater 324:701-710, 2017
Synthetic dyes	laboratory	A manganese peroxidase purified from strain CD2 decolorises azo, anthraquinone, indigo and triphenylmethane dyes and a simulated textile effluent, also in the presence of metal ions and organic solvents. Qin et al. (2014) Induction, purification and characterization of a novel manganese peroxidase from Irpex lacteus CD2. PLoS One 9:e113282, 2014

Limits

All the trials found are laboratory or bench scale, although on real soils: we found no published field trial with measured data. 4-6-ring PAHs are poorly removed (9-14%). The fungus lowers soil bacterial biomass and stresses it more than P. ostreatus does (Byss et al. 2008), which may hold back the bacterial degradation expected to finish the job.

Where it has been tried

Czech Republic, wood-preserving plant (creosote soil)

MycoremediationLaboratory, with soil from the site

Pleurotus ostreatus, Irpex lacteus

Byss, Elhottová, Tříska and Baldrian incubated the soil with the two fungi at 15 °C for 120 days, following PAHs and the microbial community.

Outcome Pleurotus ostreatus removed 55–67% of PAHs, Irpex lacteus 27–36%. By class: 86–96% (Pleurotus) and 47–59% (Irpex) of 2-ring compounds, but only 31–38% and 11–13% of 5–6-ring ones. Both fungi lowered bacterial biomass. It is a laboratory trial.