Fungus, litter decomposer

Stropharia rugosoannulata Farl. ex Murrill

Wine cap, king stropharia

A litter-decomposing mushroom, edible and easy to grow on straw and wood chips. Unlike many white-rot fungi it is a natural soil dweller, and in non-sterile soil it increases the degradation of heavy PAHs. It is also the species used in stormwater mycofiltration trials.

Ann B., Mushroom Observer, CC BY-SA 3.0

How it works

Mechanisms: mycodegradationmycofiltration
Enzymes: laccase, manganese peroxidase

Contaminants

Contaminant	Evidence	What was shown
Polycyclic aromatic hydrocarbons	laboratory	Artificially contaminated non-sterile soil (250 mg/kg total PAH), 30 days, 8 litter-decomposing species compared: with fungi up to 70% of benzo[a]anthracene, 86% of benzo[a]pyrene and 84% of dibenzo[a,h]anthracene were removed, against 29%, 26% and 43% by the indigenous microflora alone. S. rugosoannulata and S. coronilla were the most effective. Steffen et al. (2007) Enhancement of bioconversion of high-molecular mass polycyclic aromatic hydrocarbons in contaminated non-sterile soil by litter-decomposing fungi. Biodegradation 18:359-369, 2007
Explosives (TNT, RDX)	laboratory	Cell-free system: S. rugosoannulata manganese peroxidase rapidly converts aminonitrotoluenes, the main intermediates of TNT reduction (2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,6-diamino-4-nitrotoluene), with partial direct mineralisation to CO2, enhanced by thiols such as reduced glutathione or cysteine. Scheibner & Hofrichter (1998) Conversion of aminonitrotoluenes by fungal manganese peroxidase. J Basic Microbiol 38:51-59, pubmed.ncbi.nlm.nih.gov, 1998

Contaminant

Evidence

What was shown

Polycyclic aromatic hydrocarbons

laboratory

Artificially contaminated non-sterile soil (250 mg/kg total PAH), 30 days, 8 litter-decomposing species compared: with fungi up to 70% of benzo[a]anthracene, 86% of benzo[a]pyrene and 84% of dibenzo[a,h]anthracene were removed, against 29%, 26% and 43% by the indigenous microflora alone. S. rugosoannulata and S. coronilla were the most effective.

Steffen et al. (2007) Enhancement of bioconversion of high-molecular mass polycyclic aromatic hydrocarbons in contaminated non-sterile soil by litter-decomposing fungi. Biodegradation 18:359-369, 2007

Explosives (TNT, RDX)

laboratory

Cell-free system: S. rugosoannulata manganese peroxidase rapidly converts aminonitrotoluenes, the main intermediates of TNT reduction (2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,6-diamino-4-nitrotoluene), with partial direct mineralisation to CO2, enhanced by thiols such as reduced glutathione or cysteine.

Scheibner & Hofrichter (1998) Conversion of aminonitrotoluenes by fungal manganese peroxidase. J Basic Microbiol 38:51-59, pubmed.ncbi.nlm.nih.gov, 1998

Limits

The PAH data come from freshly contaminated soil, where compounds are more available than at an old site. Light PAHs are degraded by soil microbes anyway: the fungus adds something only for heavy compounds. In mycofiltration of synthetic stormwater (18.6 L columns, 600-900 cfu/100 mL E. coli) E. coli removal relative to control filters was about 20%: a real but small effect (Taylor et al. 2015). E. coli is not in the contaminant vocabulary and is not listed as a target.

Where it has been tried

Finland, old sawmill area (chlorophenols and dioxins)

MycoremediationLaboratory, with soil from the site

Stropharia rugosoannulata

Valentín, Steffen, Hatakka, Tuomela and colleagues screened white-rot and litter-decomposing fungi able to withstand the soil's own microbes, and incubated nine of them for 15 weeks in non-sterile soil or wood.

Outcome In soil the native microbes alone degraded pentachlorophenol and tetrachlorophenol as much as inoculated soil did, only more slowly. Stropharia rugosoannulata degraded 73% of PCP and 43% of 2,3,4,6-TeCP, but only 13% of dioxins and furans (as toxic equivalents). In wood, where there were no effective native degraders, white-rot fungi did better.