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pH-dependent Heavy Metal Toxicity Differentials in Fungal Isolates during Biodegradation of Spent Engine Oil

Augustine Ebele Mbachu, Nancy Amalachukwu Mbachu, Edna Ifeoma Chukwura


Indiscriminate disposal of spent engine oil is a global concern because of the numerous health risks to animals and humans following exposure. Indigenous fungi were isolated from soil samples polluted with spent engine oil (SEO) at Mgbuka-Nkpor, Nigeria. They were identified based on their cultural and microscopic characteristics and confirmed using their 18Sr RNA gene sequence. A phylogenetic tree of the isolates was constructed using the neighbour joining method. Heavy metal analysis of spent and new engine oil was conducted using Varian AA240 Atomic Absorption Spectrophotometer. The effect of varying concentrations of heavy metals on SEO degradation by the isolates at different pH levels was also determined. Two fungi isolates were obtained from this study. They were identified and confirmed as Candida tropicalis and Aspergillus clavatus. The concentration of the heavy metals (zinc, lead, cadmium and copper) was significantly higher (P < 0.05) in spent engine oil when compared to the new engine oil. There was negative inhibition (stimulation) in the media containing both the single and mixed culture of the isolates, in the presence of cadmium at pH 5.5.  Moreover, highest stimulation (20%) in SEO degradation was recorded in the presence of 10 mg/l copper at pH 5.5, in the media containing A. clavatus. These results showed that the pure and mixed culture of the isolates (C. tropicalis  and A. clavatus) have promising potential for effective bioremediation of spent engine oil polluted soil co-contaminated with cadmium and copper at pH 5.5.


Biodegradation; spent engine oil; pH-dependent; heavy metal; toxicity


Adams GO, Tawari-Fufeyin P, Igelenyah E, Odukoya E. Assessment of heavy metals bioremediation potential of microbial consortia from poultry litter and spent oil contaminated site, Inter J Environ Bioremed and Biodegrad. 2014, 2(2):84-92

Adesodun JK, Mbagwu JSC. Biodegradation of waste-lubricating petroleum oil in a tropical alfisol as mediated by animal droppings, Biores. Technol. 2008, 99(13):5659-5665

Abdulsalam S, Adefila SS, Bugaje IM, Ibrahim S. Bioremediation of soil contaminated with used motor oil in a closed system, J. Bioremed. Biodegrad. 2012, 3(12): 172

Blodgette WC. Water-soluble mutagen production during the bioremediation of oil contaminated soil, Floria Sci. 2001, 60(1): 28-36

Ekpenyong, M.G., Antai, S.P., Essien, J.P. and Iwatt, G.D. pH-dependent zinc toxicity differentials in species of Penicillium and Rhodotorula during oil biodegradation. Inter. J. Biol. Chem. 2007, 1: 54-61

Talley, J.W. Road Blocks to the implementation of Bio-Treatment Strategies. In: Bioremediation of Recalcitrant Compounds, Talley, J.W. (Eds.). CRC Press, Taylor and Francis Group, Boca Raton. 2006

Manyi-Loh, C.E., Mamphweli, S.N., Meyer, E.L., Okoh, A.I., Makaka, G. and Simon, M. Microbial anaerobic digestion (Biodigesters) as an approach to the decontamination of animal wastes in pollution control and the generation of renewable energy. Inter. J. Environ. Res. Publ. Hlth. 2013, 10 (9): 4390-4417

Olaniran, A.O., Balgobind, A. and Pillay, B. Impacts of heavy metals on 1,2-dichloroethane biodegradation in co-contaminated soil. J. Environ. Sci. 2009, 21: 661-666

Lin CY. Effect of heavy metals on acidogenesis in anaerobic digestion. Water Research, 1993, 27: 147-152

Sandrin TR, Maier RM. Impact of metals on the Biodegradation of organic pollutants, Environ. Hlth. Perspect. 2003, 11(1): 1093-1101

Mbachu AE, Chukwura EI, Mbachu NA. Isolation and characterization of hydrocarbon degrading fungi from used (spent) engine oil polluted soil and their use for polycyclic aromatic hydrocarbons (PAHs) degradation. Univ. J. Microbiol. Res. 2016a, 4(1): 31-37, DOI: 10.13189/ujmr.2016.040105

Mbachu AE, Mbachu NA, Chukwura, EI. Biodegradation of N-Alkanes by fungi isolated from waste engine oil polluted soil and their extracellular enzyme activities. International Journal of Novel Research in Life Sciences. 2016b, 3(4): 7-17

Mbachu AE, Chukwura EI, Mbachu NA. Evaluation of the effectiveness of fungi (Candida tropicalis and Aspergillus clavatus) in bioremediation of used engine oil contaminated soil using bioaugmentation technique. Inter. J. Environ. Agric. Biotechnol. 2018, 3(4): 1175-1182

Barnett, H.L. and Hunter, B.B. Illustrated Genera of Imperfect Fungi. 4th edn. Laskin, A.I. and Lechevalier, H.A. (eds). CRC Press, West Palm Beach, Florida. 2000, pp 1- 197

Watanabe, T. Morphologies of cultured fungi and key to species. In: Pictorial Atlas of Soil and Seed Fungi. 2nd edn. Haddad, S., Dery, E. Norwitz, B.E. and Lewis, R (eds). CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida. 2002: Pp 1- 486

Tamura, K., Dudley, J., Nei, M. and Kumar, S. MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) software version 4.0. Mol. Biol. Evolution, 2007: 24 (8): 1596 – 1599

Hua, L., Wu, W., Liu, Y., Tientchen, C.M., and Chen, Y. Heavy metals and PAHs in sewage sludge from twelve wastewater treatment plants in Zhejiang province. Biomed. Environ. Sci. 2008: 21: 345

Zhang S, Crow SA. Toxic effects of Ag (I) and Hg (II) on Candida albicans and C. maltose, A flow cytometric evaluation. Appl. Environ. Microbiol. 2001: 67: 4030-4035

Ekpenyong MG, Antai SP. Influence of pH on cadmium toxicity to Bacillus species (02 and 12) during biodegradation of crude oil. Inter. J. Biol. Chem.2007: 1(1): 29-37

Akpoveta OV, Egharevba F, Medjor OW, Osaro KI, Enyemike ED. Microbial degradation and its kinetics on crude oil polluted soil, Res. J. Chem. Sci. 2011: 1, 8-14

Ramasamy RK, Shankar C, Thamaraiselvi K. Evaluation of isolated fungal strain from e-waste recycling facility for effective sorption of toxic heavy metal Pb (II) ions and fungal protein molecular characterization- a mycoremediation approach, Asian J. Exp. Biol. Sci. 2011: 2 (2): 342-347

Reisewitz, A. and Martin, S. Heavy metals in motor oil have heavy consequences: In changing planet. National Geographic Society Blog. 2015

Haytham, M. and Ibrahim, M. Biodegradation of used engine oil by novel strains of Ochrobactrum anthropi HM-1 and Citrobacter freundii HM-2 isolated from oil-contaminated soil. Biotechnol. 2016: 6: 226

Wong K, Quilty B, Surif S. Degradation of crude oil in the presence of lead (Pb) and cadmium (Cd) by a metal adapted consortium culture. Adv. Environ. Biol. 2013: 7(4): 577-585

Ramasamy RK, Lee JT, Cho JY. Toxic cadmium ions removal by isolated fungal strain from e-waste recycling facility. J. Environ. Appl. Biores. 2012: 1(1): 1-4

Das, P., Mukherjee, A.K. and Sen, R. Biosurfactant of marine origin exhibiting heavy metal remediation properties. Biores. Technol. 2009: 100: 4887-4890

Iram, S., Zaman, A., Iqbal, Z. and Shabbir, R. Heavy metal tolerance of fungus isolated from soil contaminated with sewage and industrial wastewater. Polish J. Environ. Stud. 2013: 22 (3): 691-697

Price, M., Classen, J. and Payne, G. Aspergillus niger absorbs copper and zinc from swine wastewater. Biores. Technol. 2001: 77 (1): 41

Ezzouhri, L., Castro, E., Moya, M., Espinola, F. and Lairini, K. Heavy metal tolerance of filamentous fungi isolated from polluted sites in Tangier, Morocco. Afr. J. Microbiol. Res. 2009: 3(2): 35

Sani, R.K., Peyton, B.M. and Jandhyala, M. Toxicity of lead in aqueous medium to Desulfovibrio desulfuricans G20. Environ. Toxicol. Chem. 2003: 22: 252-260

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