Hydrocarbon Utilization by Culturable Microbial Species in the Rhizosphere of Eleusine indica in Oil-Polluted Soils

Abstract

The present study screened fungi species isolated from rhizosphere of Eleusine indica in some mechanic workshops in Benin City for hydrocarbon utilization. Ten different automechanic workshops were selected for the study; these were equally distributed among the 5 Local Government Areas (Egor, Oredo, Ikpoba-Okha, Ovia-North-East and Uhunmwode) in Benin City. Rhizospheric soils were obtained and analyzed for total hydrocarbon and microbial content. The results showed that total fungal colony count in the soils sampled ranged from 1.6 – 9.0 ×105 cfu/g whereas total bacterial colony count was 1.3 – 9.3 ×106 cfu/g. Total hydrocarbon contents of rhizosphere soils in the workshops ranged from 17.27ppm to as low as 0.27ppm. Saccharomycetes sp. and Aspergillus flavus were the dominant rhizospheric fungi species in the samples assayed. Five days after fungi inocula were introduced into the oil amended PDA medium THC in the Aspergillus flavus – inoculated oil-polluted media was 6.08ppm, representing 18.33% hydrocarbon utilization. Utilization by Aspergillus niger was highest (63.50%); whereas Saccharomycetes sp had the lowest percentage of utilization (0.16%). Mycelia weight of inoculated fungal species in oil-impacted PDA medium after 5 days was 0.95g in Aspergillus niger and 5.34g in Saccharomycetes sp. and 7.14g in Aspergillus flavus.
Keywords: Eleusine indica, Bioremediation, Rhizosphere, Root zone, Petroleum hydrocarbons