Bioremediation of creosote-contaminated soil by indigenous soil fungi.

Fungal isolates from a creosote contaminated land and from the soil of an uncontaminated forest floor were tested for their capabilities to colonize and degrade creosote in a soil contaminated with >25,000 mg kg(-1) (w/w) creosote. The fungi included two strains of basidiomycete both of which were Pleurotus sp., one from the contaminated soil and the other from an uncontaminated forest floor, and four strains of non-basidiomycete fungi, Cladosporium sp., Fusarium sp., Penicillium sp. and Aspergillus sp., from the contaminated soil. Soil analyses was done by Soxhlet extraction and gas chromatography (Eriksson et al.,2000), to effect the separation of volatile and heavy components of creosote. The non-basidiomycete were found to remove between 78% and 88% creosote from the soil within the 70 days of treatment. Pleurotus sp. was found to remove up to 94% of the initial creosote concentration. A composite mixture of all the isolates from the contaminated soil showed better creosote removal from the soil. Barley as a bulking agent, N and P supplementation and aeration were observed to influence the rate of growth of all the fungi and improve on the removal of creosote from the soil. The results showed that fungi can be effectively used to remediate creosote contaminated soils provided that adequate conditions are provided. Studies are presently underway to find means of sustaining the growth of the fungi for longer periods for use in large scale application in bioremediation.