Fungal Population Dynamics Associated with Active-phase of Hydrocarbon Degradation in Oil-polluted Soil

Abstract

Fungal population dynamics was monitored in an oil-polluted soil undergoing remediation by enhanced natural attenuation (RENA) at Ibaa, Emohua L. G. A. Rivers State. Total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) were determined from baseline [pre-RENA (POL B)] and sampling days 0 (POL 0), 9 (POL 9), 18 (POL 18), 36 (POL 36) and day 56 (POL 56)] using gas chromatographic-mass spectrometry.  The baseline TPH and PAHs were 9,146.65 ppm and 3,454.10 ppm in the polluted soil (pre-RENA) and 479.67 ppm and 279.72 ppm for unpolluted soil (pristine control) respectively. By day 56, percentages of contaminants degradation were 97% and 89% for TPH and PAHs respectively. Higher counts for both heterotrophic fungal (THF) counts and culturable hydrocarbon utilizing fungal (HUF) counts were obtained on day 36 with values of 5.6 x 105 cfu/g and 4.77 x 106 cfu/g respectively. Out of the 47 HUF isolated and characterized, 34 hydrocarbon utilizing fungi were isolated in the active phase between day 9 (POL 9) to day 36 (POL 36).  These recovered hydrocarbon degrading fungal isolates associated with the active phase of hydrocarbon degradation (Mucor sp., Malbranchia sp., Prototheca sp., Cladosporium spp., Trichosporon sp., Acremonium spp., Rhizomucor spp.). RENA treatment effectively reduced the pollutant levels in the impacted soil.