Furthermore, a recent study evaluated the feasibility of exploiting P. ostreatus
spent mushroom substrate (SMS-a low-cost waste of the industrial production of this
fungus) to treat PCB-contaminated soil coming from a former industrial area (Siracusa et al. 2017). The fungal treatment was firstly assessed at mesocosm scale, and
then validated at pilot scale. In the latter test, 94.1% of the PCB degradation was
observed in dynamic biopiles when the soil was mixed in a ratio of 10% w/w with
P. ostreatus substrate.
Compared with the PCB biotransformation processes mediated by basidiomycetes, few studies investigated the PCB biodegradation potential of non-ligninolytic
fungi. Most of the reports referred to liquid culture laboratory tests to evaluate the
degradation capabilities of these fungi towards technical mixture of PCBs: Aspergillus niger (Dmochewitz and Ballschmiter 1988), Aspergillus, Penicillium, Fusarium and Scedosporium genera isolated from an aged PCB-contaminated soil (Tigini
et al. 2009) and Doratomyces spp. Myceliophthora thermophila, Phoma eupyrena
and Thermoascus crustaceus (Mouhamadou et al. 2013).
With regard to ascomycetes, a fungal consortium was used for the remediation of
both PCB-contaminated soil and sediment (Sage et al. 2014). In this study, 18.7 and
33.3% of 15 target PCBs were degraded in soil and sediment mesocosms, respectively, after 6 months of treatment. Afterwards, the fungal strains were re-inoculated.
However, no additional PCB depletion was observed within another 2 months of
treatment suggesting that the bioavailable fraction of PCB had already been
completely removed and the remaining fraction was inaccessible to fungi.
22.4.2 Chlorinated Dioxins and Furans
Polychlorinated dibenzodioxins (PCDDs) are a group of polyhalogenated organic
compounds that consist of two benzene rings joined by two oxygen bridges
(dibenzo-1,4-dioxin) with one or several chlorine substituents replacing hydrogen
atoms. Polychlorinated dibenzofurans (PCDFs) are a group of organopollutants with
properties and chemical structures similar to PCDDs. PCDDs and PCDFs are
released into the environment as by-products of several industrial processes (i.e.,
incineration of waste, chemical processes, and manufacturing of pesticides). They
can be easily accumulated in humans and wildlife because of their lipophilic
properties. Further, they can cause developmental disorders and cancer, as already
reported several decades ago (Huff et al. 1980). For this reason, they were listed
among the most persistent hazardous organic pollutants in the Stockholm
convention.
Several white-rot fungi were assessed for their ability to degrade chlorinated
dioxins in model liquid systems. At first, the oxidation of 2,3,7,8tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD) (Bumpus et al. 1985) and
2,7-dichlorodibenzo-p-dioxin (2,7-diCDD) (Valli et al. 1992) by the white-rot fungus P. chrysosporium under ligninolytic conditions was demonstrated. Thereafter,
450
T. Stella
spent mushroom substrate (SMS-a low-cost waste of the industrial production of this
fungus) to treat PCB-contaminated soil coming from a former industrial area (Siracusa et al. 2017). The fungal treatment was firstly assessed at mesocosm scale, and
then validated at pilot scale. In the latter test, 94.1% of the PCB degradation was
observed in dynamic biopiles when the soil was mixed in a ratio of 10% w/w with
P. ostreatus substrate.
Compared with the PCB biotransformation processes mediated by basidiomycetes, few studies investigated the PCB biodegradation potential of non-ligninolytic
fungi. Most of the reports referred to liquid culture laboratory tests to evaluate the
degradation capabilities of these fungi towards technical mixture of PCBs: Aspergillus niger (Dmochewitz and Ballschmiter 1988), Aspergillus, Penicillium, Fusarium and Scedosporium genera isolated from an aged PCB-contaminated soil (Tigini
et al. 2009) and Doratomyces spp. Myceliophthora thermophila, Phoma eupyrena
and Thermoascus crustaceus (Mouhamadou et al. 2013).
With regard to ascomycetes, a fungal consortium was used for the remediation of
both PCB-contaminated soil and sediment (Sage et al. 2014). In this study, 18.7 and
33.3% of 15 target PCBs were degraded in soil and sediment mesocosms, respectively, after 6 months of treatment. Afterwards, the fungal strains were re-inoculated.
However, no additional PCB depletion was observed within another 2 months of
treatment suggesting that the bioavailable fraction of PCB had already been
completely removed and the remaining fraction was inaccessible to fungi.
22.4.2 Chlorinated Dioxins and Furans
Polychlorinated dibenzodioxins (PCDDs) are a group of polyhalogenated organic
compounds that consist of two benzene rings joined by two oxygen bridges
(dibenzo-1,4-dioxin) with one or several chlorine substituents replacing hydrogen
atoms. Polychlorinated dibenzofurans (PCDFs) are a group of organopollutants with
properties and chemical structures similar to PCDDs. PCDDs and PCDFs are
released into the environment as by-products of several industrial processes (i.e.,
incineration of waste, chemical processes, and manufacturing of pesticides). They
can be easily accumulated in humans and wildlife because of their lipophilic
properties. Further, they can cause developmental disorders and cancer, as already
reported several decades ago (Huff et al. 1980). For this reason, they were listed
among the most persistent hazardous organic pollutants in the Stockholm
convention.
Several white-rot fungi were assessed for their ability to degrade chlorinated
dioxins in model liquid systems. At first, the oxidation of 2,3,7,8tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD) (Bumpus et al. 1985) and
2,7-dichlorodibenzo-p-dioxin (2,7-diCDD) (Valli et al. 1992) by the white-rot fungus P. chrysosporium under ligninolytic conditions was demonstrated. Thereafter,
450
T. Stella