Crude Oil Bioremediation Efficiency of Indigenous Soil Fungal Community Spiked with Cassava Peels in Niger Delta Region, Nigeria

Abstract

The bio-stimulation potential of cassava peels (CP) on crude oil degradation by indigenous fungal flora was investigated in soil microcosm. Air dried, sieved (2.00 mm) composite top soil (0-20 cm depth) samples were measured into four plastic buckets (2 kg each) and artificially contaminated by applying 200 ml of crude oil and left for one week. Each contaminated soil sample was then mixed thoroughly with pulverised pre-sieved (2.00 mm) cassava peels (CP) at various concentrations (100 - 400 g) and incubated at room temperature with periodic addition of moisture and thorough mixing for 42 days. Soil sampling was done at 14 days' interval post one-week soil acclimatization period for hydrocarbon degradation, total heterotrophic fungi counts (THFC) and utilization (HUFC), and pH using standard techniques. Results revealed that the percentage of crude oil hydrocarbon degradation was higher in CP amended crude oil treated soils. The highest hydrocarbon degradation (78.67 %) recorded was observed in the 400 g CP amendment as against 45.21 % biodegradation in un-amended control. The THFC and HUFC were significantly (P < 0.05) higher in CP spiked soils than in the un-amended controls. A wider pH variation was observed in the un-amended soil (6.88 – 7.92) than the CP amended soils (6.76 – 6.98) after 42 days. The indigenous hydrocarbon degrading fungal genera isolated were Rhizopus sp., Fusarium sp., Apergillus sp, Mucor sp., Geotrichum sp., Curvularia sp., Penicillium sp., Aternaria sp., Cladosporiumsp., Trichoderma sp., and Botrytissp.The results of this study suggest that cassava peels, like some other agricultural waste, could be considered as a potential bio-stimulating agent for bioremediation of crude oil polluted soils in Niger Delta where these wastes are massively generated and dumped indiscriminately.