Studies on relative capabilities of bacterial and yeast isolates from tropical soil in degrading crude oil
Introduction
Frequent oil spills are inevitable in oil producing areas like the Niger Delta Area of Nigeria. Oil spills devastate soil and aquatic ecosystems, and cause alteration in important microbial processes. This therefore necessitates studies in microbial degradation of crude oil as a means of clearing up oil polluted environments. Specifically, such studies are directed towards the isolation and identification of superior crude oil degrading microorganisms from soil and aquatic ecosystem. Besides, studies on the rate and total extent of crude oil degradation by microbial isolates are important as these will enable the oil industries to explore the possibility of using the efficient crude oil degraders for seeding oil polluted environments, particularly in areas with difficult terrain, where mechanical clean-up operations are not possible. The Niger Delta Area of Nigeria from where two of the isolates used in this study were isolated have difficult terrain and present problems in oil spill abatement using non-biological approaches.
The relative contribution of bacteria and fungi to hydrocarbon mineralization in soil has been reported by Song et al.[1]. The investigators observed that in a sandy loam soil with no history of hydrocarbon pollution, 82% of n-hexadecane was mineralized by bacteria whereas fungi were able to mineralize only 13% of the hydrocarbon. Similarly, many other investigators have reported2, 3, 4, 5, 6the involvement of bacteria and yeasts in crude oil biodegradation. In these reports, bacteria have been identified as more efficient crude oil degraders than yeasts. On the contrary, there is scanty information that yeasts are better crude oil degraders than bacteria[7]. The present study contributes information in this area.
The growth of microorganisms on hydrocarbons is often accompanied by the emulsification of the insoluble carbon source in the culture medium8, 9, 10. In most cases, this has been due to the production of extracellular emulsifying agents during the breakdown of hydrocarbons. The propensity of hydrocarbon grown microorganism to adhere to hydrocarbon has also been reported11, 12, 13. These processes aid microorganisms in growing on and metabolizing crude oil.
The aims of the present study were to investigate the relative capabilities of two bacterial isolates from oil polluted soil and a yeast isolate from unpolluted soil, in degrading a Nigerian light crude oil, transniger pipeline crude and to examine their ability to adhere to and emulsify crude oil so that the results could point to a better candidate for cleaning up oil spills in tropical soils.
Section snippets
Materials and methods
Mineral salts medium (MSM) of Zajic and Supplisson[14]and oil agar (OA) were used for biodegradation studies. The MSM had the following composition: 1.8 g K2PO4, 1.2 g KH2PO4, 4.0 g NH4Cl, 0.2 g MgSO4 · 7H2O, 0.1 g NaCl, 0.01 g FeSO4 · 7H2O in 1 l of distilled water (pH 7.4). Oil agar is MSM plus 1.0% crude oil and 20 g of agar (Oxoid).
Results
Based on rapid growth on crude oil and their considerably high ability in degrading crude oil, two isolates designated COU-27 and OCS-21, out of the 20 crude oil degrading bacterial isolates and one (PFS-95) out of the 10 crude oil degrading yeast isolates screened, were selected for this study. COU-27 was isolated from crude oil polluted soil while OCS-21 and PFS-92 were isolated from crude oil free soil. It was observed that bacterial isolate OCS-21 was a gram negative, motile rod while
Discussion
Soil microorganisms participate in soil processes including transformation of nutrients. They are also active degraders of crude oil3, 4, 5, 6, 18, 21, 22. The present study revealed that crude oil degrading microorganisms are not restricted to oil polluted soil as A. calcoaceticus COU-27 and C. tropicalis PFS-95 isolated from soil with no history of oil pollution and S. marcescens OCS-21 isolated from oil polluted soil degraded crude oil. This finding supports the report of Odu23, 24that crude
Acknowledgements
The author is grateful to Prof. Dr. B. Witholt for providing financial assistance and facilities for this study. Dr. Hans Preusting is also acknowledged for his assistance with the GLC analysis. The author wishes to thank Prof. S.P. Antai, Prof. E.D. Okon and Dr. A.A. Opara for their suggestions and the Nigerian National petroleum Corporation (NNPC) for the provision of the crude oil sample used in this study.
References (32)
- Song HG, Predersen TA, Bartha R. Hydrocarbon mineralization in soil: Relative bacterial and fungal contribution. Soil...
- Fedorak PM, Semple KM, Westlake DWS. Oil degrading capabilities of yeasts and fungi isolated from coastal marine...
- Okpokwasili GC, Amanchukwu SC. Petroleum hydrocarbon degradation by Candida species. Environment International...
- Antai SP, Mgbomo E. Distribution of hydrocarbon utilizing bacteria in oil-spill areas. Microbios Letters...
- Antai SP, Mgbomo E. Pattern of degradation of Bonny light crude oil by Bacillus sp. and Pseudomonas sp. isolated from...
- Amund OO, Akangbou TS. Microbial degradation of four Nigerian crude oil in an estaurine microcosm. Letters in Applied...
- Walker JD, Petrakis L, Colwell RR. Degradation of petroleum by pure cultures of bacteria, algae, yeasts and filamentous...
- Reddy PG, Singh HD, Roy PK, Buruah JN. Predominant role of hydrocarbon solubilization in the microbial uptake of...
- Hommel RK. Formation and physiological role of biosurfactants produced by hydrocarbon-utilizing microorganisms....
- Rosenberg E. Exploiting microbial growth in hydrocarbons – new markets. Trends in Biotechnology...
Cited by (82)
Bioremediation of soil: an overview
2022, Microbes and Microbial Biotechnology for Green RemediationAdvancement in bioinformatics and microarray-based technologies for genome sequence analysis and its application in bioremediation of soil and water pollutants
2020, Microbe Mediated Remediation of Environmental ContaminantsMicrobial remediation progress and future prospects
2020, Bioremediation of Pollutants: From Genetic Engineering to Genome EngineeringExploring Microbial Diversity and Function in Petroleum Hydrocarbon Associated Environments Through Omics Approaches
2019, Microbial Diversity in the Genomic EraFungal diversity associated with crude oil-impacted soil undergoing in-situ bioremediation
2018, Sustainable Chemistry and PharmacyCitation Excerpt :Allamin et al. (2014) identified Aspergillus, Penicillium and Rhizopus species as their hydrocarbon utilizing fungi isolates from Kukawa, Borno State, Nigeria. These organisms have been previously identified as hydrocarbon degraders (Ijah, 1998; Zhang et al., 2006; Kayode-isola et al., 2008; Abioye et al., 2012). They reported thet Aspergillus niger and Penicillium notatum amongst other fungi utilize hydrocarbon more while Aspergillus fumigates, Aspergillus oryzae and Rhizopus oryzae exhibited moderate ability in degrading oil.