DETERMINATION OF DEGRADING ABILITY OF FUNGI ISOLATED FROM HYDROCARBON POLLUTED SOIL ON CRUDE OIL USING GAS CHROMATOGRAPHY
Crude oils are composed of mixtures of paraffin, alicylic and aromatic hydrocarbons. Microbial communities exposed to hydrocarbons become adapted, exhibiting selective enrichment and genetic changes resulting in increased proportions of hydrocarbon-degrading bacteria and bacterial plasmids encoding hydrocarbon catabolic genes (Leahy and Colwell, 2004). Adapted microbial communities have higher proportions of hydrocarbon degraders that can respond to the presence of hydrocarbon pollutants. The measurement of biodegradation rates under favorable laboratory conditions using 14C-labelled hexadecane has led to the estimation that as much as 0.5 – 60 g oil/m3 seawater convert to carbon dioxide, depending on temperature andmineral nutrient conditions. The principal forces limiting the biodegradation of polluting petroleum in the sea are the resistant and toxic components of oil itself, low water temperatures, scarcity of mineral nutrients (especiallynitrogen and phosphorous), the exhaustion of dissolvedoxygen and in previously unpolluted areas, the scarcity ofhydrocarbon-degrading microorganisms (Atlas, 2002).Low winter temperature can limit rates of hydrocarbonbiodegradation increasing resident time of oil pollutant(Bodennec et al., 2007).Bio-degradation is nature's way of recycling wastes, or breaking down organic matter intonutrients that can be used and reused by other organisms.
In the microbiological sense,"bio-degradation" means that the decaying of all organic materials is carried out by a hugeassortment of life forms comprising mainly bacteria and fungi, and other organisms. This pivotal,natural, biologically mediated process is the one that transforms hazardous toxic chemicals intonon-toxic or less toxic substances. In a very broad sense, in nature, there is no waste becausealmost everything gets recycled. In addition, the secondary metabolites, intermediary moleculesor any ‘waste products’ from one organism become the food/nutrient source(s) for others,providing nourishment and energy while they are further working-on/breaking down the so called waste organic matter. Some organic materials will break down much faster than others, but all will eventually decay.By harnessing microbial communities, the natural “forces” of biodegradation, reduction of wastes and clean up of some types of environmental contaminants can be achieved. There are several reasons for which this process is better than chemical or physical processes. For example, this process directly degrades contaminants rather than merely transforming them from one form to the other, employ metabolic degradation pathways that can terminate with benign terminalproducts like CO2 and water, derive energy directly form the contaminants themselves, and canbe used in situ to minimize the disturbances usually associated with chemical treatment at theclean-up sites. Biological degradation of organic compounds may be considered an economicaltool for remediating hazardous waste-contaminated environments. While some environmentsmay be too severely contaminated for initial in situ treatment to be effective, most contaminatedmedia will use some form of biological degradation in the final treatment phase.
Diverse groups of fungi have been isolated from oil contaminated environments and/or have been shown to degrade hydrocarbons in the laboratory. Microbial degradation is themajor mechanism for the elimination of spilled oil from theenvironment ( Atlas, 2000.). In this study, crude oil-contaminated soil samples areas in delta state were examined with the aimof isolating fungi withhigh crude oil degrading potentials.
1.1 Justification of the study
Various studies have identified some micro-organisms to be able to degrade crude oil. The degrading ability of these micro organisms have been determined using different methods such as gas chromatography and mass spectrometry (GC/MS), gas chromatography (GC), turbidometry, titrimetry e.t.c. Bio-degredation of crude oil is majorly carried out by bacteria and fungi. This study scientifically justifies the use of fungi to degrade crude oil. This project was therefore carried out to determine the degrading ability of fungi isolated from crude oil-contaminated soil samples using gas chromatography.
1.2 Objective of the study
The specific objectives of the study are to :
I. Isolate and identify fungi from crude oil-contaminated soil sample.
II. Screen the isolates for bio-degradative abilities.
III. Assessment of the degrading abilities of the fungi isolates by gas chromatography
6.0 CONCLUSION AND RECOMMENDATION
Microbial activities are very important for the renewal of our environment and maintenance ofthe global carbon cycle.(Ojumu, 2004). These activities are included in the term bio-degradation. Amid them substances that can be degraded or transformed by microorganisms are a huge number ofsynthetic compounds and other chemicals having ecotoxicological effects like hydrocarbons. Fungiare excellent hydrocarbon degraders and show tremendous diversity and adaptability in utilization of crude oil as a carbon sourceas seen in this study. However theirabilities to degrade a specific hydrocarbon as a source of energy and/or biomassmay differ. (Davies and Westlake, 1979).Therefore, it can be said that fungi can be used to degrade hydrocarbon and its derivatives.
Furthermore, due to the high level of degradation of crude oil by Aspergillusniger as seen in the gas chromatography analysis, it can be concluded that Aspergillusniger can be employed in successful large scale bioremediation of pollutants such as hydrocarbons thereby making a difference inour ability to reduce wastes, eliminate industrial pollution, and enjoy a more sustainable future.
The crude oil samples should be taken for further analysis such as gas chromatography and mass spectrometry.
There should be an increased focus on the use of fungi to degrade crude oil because they are very effective and prominent in the bio-degradation process and also, some studies have it that fungi are more effective than bacteria in mopping up oil spills..