CHAPTER ONE
1.0 INTRODUCTION
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.Fungi Isolated
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.Fungi Isolated