Microbial Remediation of Pesticides - Pesticides: Evaluation of Environmental Pollution - page 138

5.5 Fungi
Soil bioremediation using fungi is a promising technique to clean up soil contaminated
especially with organic compounds. Fungal remediation techniques rely not only on suit-
able organisms obtained through screening but also on their inoculation and interaction
with natural soil microflora. Therefore, several feasible application techniques have been
tested (Table 5.5), but they are still not largely in use. Modern techniques utilize fungi to
degrade larger and more recalcitrant molecules and combine them with the natural ability
of the soil microflora to handle part of the cleaning process (Steffen and Tuomela 2010).
Persistence of pesticides depends on their binding to other components and subsequent
degradation. Environmental conditions at the time of application, such as pH, temperature,
soil, and especially water content, have a great impact on the ability of fungi to degrade
pesticides (Amauri et al. 2010). For example, use of laccase from white-rot fungi Panus
conchatus showed that soil oxygen conditions and soil pH have significant effects on the
remediation of DDT-contaminated soil. This study found a positive correlation between
the concentration of oxygen in soil and the degradation of DDT by laccase. The residues
of DDTs in soils treated with laccase were lower at pH range 2.5-4.5 (Zhao and Yi 2010).
A recent study showed that Trametes versicolor and Pleurotus ostreatus were very efficient
degraders and degraded the pesticides imazalil, thiophanate methyl, ortho-phenylphenol,
diphenylamine, and chlorpyrifos (Karas et al. 2010). The endophytic fungus Ceratobasidium
stevensii (strain B6) isolated from Bischofia polycarpa showed a high degradation efficiency
of phenanthrene (Dai et al. 2010). Not only the fungal strain but even the spent mushroom
waste from Pleurotus ostreatus degraded DDT by 40% and 80% during a 28-day incubation
in sterilized and unsterilized soil, respectively (Purnomo et al. 2010). Trichoderma sp. Gc1
was observed to be capable of degrading 58% of DDD after 14 days (Ortega et al. 2010).

TABLE 5.5
List of Fungal and Cyanobacterial Taxa Capable of Degrading Pesticides

Organism Used Pesticides References

Fungi
Panus conchatus 1,1,1-Trichloro-2,2-bis (4-chlorophenyl) ethane

(DDT)

Zhao and Yi (2010)

Trametes versicolor and
Pleurotus ostreatus

imazalil, thiophanate methyl, ortho-
phenylphenol, diphenylamine, and
chlorpyrifos

Karas et al. (2010)

Ceratobasidium stevensii Phenanthrene Dai et al. (2010)

Pleurotus ostreatus 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane

(DDT)

Purnomo et al. (2010)

Trichoderma sp. Dichlorodiphenyldichloroethane (DDD) Ortega et al. (2010)

Ganoderma australe Lindane Dritsa et al. (2009)

Aspergillus oryzae Organophosphorus pesticides such as

monocrotophos

Bhalerao and Puranik (2009)

Phlebia brevispora Dieldrin Kamei et al. (2010)

Cyanobacteria
Spirulina platensis

Chlorpyrifos Thengodkar and Sivakami (2010)

Microcystis novacekii Methyl parathion (an organophosphorus

pesticide)

Fioravante et al. (2010)