Bioremediation of petroleum refinery wastewater by fungal stains isolated from the fishing harbour of Bizerte (Mediterranean Sea)

Abstract

The study was conducted in order to explore the potential of fungi isolated from surface and bottom seawater collected from the fishing harbour of Bizerte on the bioremediation of industrial effluent (IE) contaminated by petroleum hydrocarbon. Among the 128 fungal isolates, 11 were isolated from surface seawater and 7 from bottom seawater, representing 18 taxa in total. The gas chromatography mass spectrometry (GC–MS) was used for the determination of hydrocarbon compounds in IE. An initial screening of fungal growth using six concentrations ranged between 20 and 70% (v/v) IE has allowed the identification of the optimal concentration for fungal growth as well as selection of species able to tolerate high amounts of hydrocarbon. Colorimetric test employing 2,6-dichlorophenol indophenol and gravimetric method was applied for the assessment of fungal growth using 20% EI. By checking the phylogenetic affiliation of the high-performing stains as identified using ITSr DNA sequence, a dominance of Ascomycetes was detected. Indeed, Aspergillus terreus and Penicillium expansum may degrade 82.07 and 81.76% of residual total petroleum hydrocarbon (TPH), respectively. Both species were collected from surface seawater. While, Aspergillus niger, Colletotrichum sp and Fusarium annulatum displayed comparable degradation rates 40.43%, 41.3%, and 42.03%, respectively. The lowest rate of degradation 33.62% was detected in Emericellopsis phycophila. All those species were isolated from bottom seawater, excepting A. niger isolated from surface water. This work highlighted the importance of exploring the potential of fungi isolated from the natural environment on the bioremediation of industrial effluent. Our results promoted the investigation of the potential of the high-performing isolates A. terreus and P. expansum on the bioremediation of IE at pilot-scale and then in situ.