The use of fungi was evaluated for the remediation of creosote-contaminated soil
at a wood-preserving site in West Virginia (Lamar et al. 2002). At first, a preliminary
bench-scale test was carried out to assess the degradation capabilities of two WRFs,
namely P. ostreatus and I. lacteus. Afterwards, P. ostreatus from a commercial
spawn provider was selected to scale up the process and two treatment biocells were
set up at pilot scale. The contaminated soil was mixed with a sterile substrate (wood
splinters or wood splinters with sawdust) and P. ostreatus spawn. The concentration
of all the 16 PAHs was reduced in both biocells below the industrial risk-based level
in 276 days with the exception of benzo[a]pyrene (Lamar et al. 2002).
P. ostreatus-based treatment was evaluated for the remediation of
PAH-contaminated soils under field conditions also in the Northern temperate
zone (Hestbjerg et al. 2003). The contaminated soils were collected from two
different areas of an asphalt factory: a former shipyard and a coal tar storage.
Concrete cylinders were filled with both soils and used to test different conditions:
non-amended soil (control), soil mixed with autoclaved sawdust substrate, and soil
mixed with P. ostreatus spawn. In the case of the soil from the coal tar storage, the
addition of the oyster mushroom significantly enhanced the degradation rate of
4-ring PAHs compared to the rate in either soil control or biostimulated cylinder,
while 5- and 6-ring PAHs were only slightly removed and no significant difference
was observed between the two treatments. By contrast, the growth and the activity of
P. ostreatus were completely prevented when inoculated in the other soil, although
the factors that resulted in its inefficacy were not clarified.
22.7 The Potentialities and Drawbacks of Soil
Mycoremediation
The potentialities of using both ligninolytic and non-ligninolytic fungi for the
degradation of persistent chlorinated and non-chlorinated organopollutants in contaminated soils have been clearly demonstrated through a number of studies at
laboratory scale since the 1980s.
However, as it was highlighted in the previous section, the low number of largerscale trials showed remarkable limitations in the practical application of fungalbased technologies. Consequently, all the attempts to promote soil mycoremediation
on the market as a valuable on-site bioremediation option have failed (Šašek 2003;
Baldrian 2008).
One of the reasons that limited the use of the fungal-augmentation strategy in the
remediation of contaminated soils was the competition between the inoculated fungi
and the autochthonous soil microorganisms. Indeed, when a single allochthonous
fungal species is introduced into soil, its colonization, growth, and metabolism are
strongly affected by the type and activity of other resident soil organisms. Moreover,
the inoculation carrier onto which fungi are immobilized prior to their introduction in
non-sterile soil (e.g., straw, corn cobs, seeds husks, wood chips or shavings, and
456
T. Stella
at a wood-preserving site in West Virginia (Lamar et al. 2002). At first, a preliminary
bench-scale test was carried out to assess the degradation capabilities of two WRFs,
namely P. ostreatus and I. lacteus. Afterwards, P. ostreatus from a commercial
spawn provider was selected to scale up the process and two treatment biocells were
set up at pilot scale. The contaminated soil was mixed with a sterile substrate (wood
splinters or wood splinters with sawdust) and P. ostreatus spawn. The concentration
of all the 16 PAHs was reduced in both biocells below the industrial risk-based level
in 276 days with the exception of benzo[a]pyrene (Lamar et al. 2002).
P. ostreatus-based treatment was evaluated for the remediation of
PAH-contaminated soils under field conditions also in the Northern temperate
zone (Hestbjerg et al. 2003). The contaminated soils were collected from two
different areas of an asphalt factory: a former shipyard and a coal tar storage.
Concrete cylinders were filled with both soils and used to test different conditions:
non-amended soil (control), soil mixed with autoclaved sawdust substrate, and soil
mixed with P. ostreatus spawn. In the case of the soil from the coal tar storage, the
addition of the oyster mushroom significantly enhanced the degradation rate of
4-ring PAHs compared to the rate in either soil control or biostimulated cylinder,
while 5- and 6-ring PAHs were only slightly removed and no significant difference
was observed between the two treatments. By contrast, the growth and the activity of
P. ostreatus were completely prevented when inoculated in the other soil, although
the factors that resulted in its inefficacy were not clarified.
22.7 The Potentialities and Drawbacks of Soil
Mycoremediation
The potentialities of using both ligninolytic and non-ligninolytic fungi for the
degradation of persistent chlorinated and non-chlorinated organopollutants in contaminated soils have been clearly demonstrated through a number of studies at
laboratory scale since the 1980s.
However, as it was highlighted in the previous section, the low number of largerscale trials showed remarkable limitations in the practical application of fungalbased technologies. Consequently, all the attempts to promote soil mycoremediation
on the market as a valuable on-site bioremediation option have failed (Šašek 2003;
Baldrian 2008).
One of the reasons that limited the use of the fungal-augmentation strategy in the
remediation of contaminated soils was the competition between the inoculated fungi
and the autochthonous soil microorganisms. Indeed, when a single allochthonous
fungal species is introduced into soil, its colonization, growth, and metabolism are
strongly affected by the type and activity of other resident soil organisms. Moreover,
the inoculation carrier onto which fungi are immobilized prior to their introduction in
non-sterile soil (e.g., straw, corn cobs, seeds husks, wood chips or shavings, and
456
T. Stella