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Biodegradation
of PAHs by fungi in contaminated-soil containing cadmium and
nickel ions
Harrison Ifeanyichukwu Atagana
Institute for Science and Technology Education, University
of South Africa, Pretoria, South Africa. E-mail:
atagahi@unisa.ac.za.
Accepted 8 May, 2009 |
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The study investigated the degradation of the
polycyclic aromatic hydrocarbons (PAH) benzo(a)anthracene,
benzo(a) fluoranthene, benzo(a) pyrene, chrysene and
phenanthrene in a soil that was sterilized and inoculated
with the nonligninolytic fungi, Fusarium flocciferum
and Trichoderma spp. and the ligninolytic fungi,
Trametes versicolor and Pleurotus ostreatus in
the presence of cadmium (Cd) and nickel (Ni) during a ten
week incubation period. The soil pH was initially 5.3 and
after amendment increased to 7.0. The fungi degraded the
tested PAHs between 21 and 93% by the end of the tenth week.
The fungi degraded the less-soluble PAHs containing five or
six aromatic rings more slowly than those containing fewer
aromatic rings. Although the presence of cadmium
and nickel in the soil affected the activity of the enzymes
produced by the fungi, no significant decrease in
PAH degradation was found in the contaminated soil
containing 50 or 100 mg kg-1 of Cd and Ni.
However, at 300 and 500 mg kg-1, degradation of
the PAHs by the fungi was impaired and the severity of the
impairments increased with the increase in the
concentrations of Cd and Ni. This was probably due
to the lack of the activities of some enzymes such as
Mn-dependent peroxidase, which could have resulted from the
poor colonization of the fungi at these concentrations.
Key words:
Bioremediation, fungi, heavy metals, PAHs, soil. |
