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Microbial degradation of crude oils

Gilbert, Paul Douglas (1980) Microbial degradation of crude oils. Doctor of Philosophy (PhD) thesis, University of Kent. (doi:10.22024/UniKent/01.02.94366) (KAR id:94366)

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The microbial degradation of two crude mineral oils and one synthetic crude oil was studied under In situ estuarine conditions and in the laboratory. The three oils differed widely in composition; the Athabasca synthetic crude was a light oil with a high saturate content, conversely its parent sand tar was a heavy oil low in saturates. The North Sea Forties crude represented an intermediate between these two extremes.

A new environmental experimental system was devised to yield quantitative data on oil degradation and this was deployed in the Medway estuary under both winter and summer conditions between December 1976 and July 1978. During both winter and summer experiments oil composition had a major influence on the rate and extent of oil loss which followed the order, synthetic crude > Forties crude > sand tar. This order conforms to predictions made on the basis of the fractional composition of the oils. The saturate fraction of the Forties crude and sand tar was most extensively degraded during the second summer experiment. Temperature rather than inorganic nutrient supply appeared to limit degradation during the winter months; degradation was more rapid during the summer months. Microbial colonization of the oils was predominantly bacterial and was more rapid during the summer. The overall colonization pattern however was similar for each oil throughout both winter and summer experiments .

The laboratory experiments using supplemented media broadly confirmed the degradation patterns found during the in situ experiments. However, higher initial degradation rates for all the oils were found at 25°C in supplemented medium than those occurring in the in situ summer experiments. The laboratory- experiments also revealed the interesting phenomena of novel hydrocarbon synthesis and the occurrence of intracellular hydrocarbon inclusions during growth on the Forties crude and synthetic crude respectively.

Item Type: Thesis (Doctor of Philosophy (PhD))
DOI/Identification number: 10.22024/UniKent/01.02.94366
Additional information: This thesis has been digitised by EThOS, the British Library digitisation service, for purposes of preservation and dissemination. It was uploaded to KAR on 25 April 2022 in order to hold its content and record within University of Kent systems. It is available Open Access using a Creative Commons Attribution, Non-commercial, No Derivatives ( licence so that the thesis and its author, can benefit from opportunities for increased readership and citation. This was done in line with University of Kent policies ( If you feel that your rights are compromised by open access to this thesis, or if you would like more information about its availability, please contact us at and we will seriously consider your claim under the terms of our Take-Down Policy (
Uncontrolled keywords: Microbiology; environmental studies
Subjects: Q Science > QH Natural history
Q Science > QR Microbiology
Divisions: Divisions > Division of Natural Sciences > Biosciences
SWORD Depositor: SWORD Copy
Depositing User: SWORD Copy
Date Deposited: 16 Jun 2022 14:53 UTC
Last Modified: 18 Jul 2022 13:01 UTC
Resource URI: (The current URI for this page, for reference purposes)

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