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Title: Dynamics of sediment microbial communities following hydrocarbon exposure
Author: Potts, Lloyd Douglas
ISNI:       0000 0004 7967 6571
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2019
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Continued exploration and production of petroleum hydrocarbons (HCs) within the marine environment carries the risk of oil pollution, followed by their transportation to the seabed. HCs modify microbial community structure resulting in selection of HC-degrading microorganisms. However, the mechanisms of microbial community assembly and dynamics are not well understood. This thesis aims to elucidate these processes with the following hypotheses: (1) microbial communities shift following HC exposure due to selection of HCdegraders, (2) environmental parameters (such as temperature) control microbial community structure and influence HC degradation rates, and (3) chronic pollution of sediments influence community assembly processes and result in a pre-adapted community. To test these hypotheses a series of experiments were designed. Firstly, oil deposition to deepsea sediments and dispersant application was simulated in cores to examine microbial dynamics. Secondly, differences in community structure controlled by marine depth on HC degradation ability were evaluated using crude oil-enriched microbial consortia. Finally, microbial community assembly processes following hydrocarbon exposure were investigated in a range of polluted sediments. Microbial communities were characterised by sequencing 16S rRNA gene and HC degradation potential was assessed by gas chromatography. Oil deposition prompted microbial successional shifts caused by selection of HC-degraders. This implies a rapid response of bacterial communities, accelerated by dispersant, following deep-sea sediment pollution and could be exploited in oil pollution monitoring technology. Higher degradation potential of shallow-sediment consortia compared to deep-sea consortia indicates the effect of in situ conditions on community structure and influences remediation potential. Highly polluted river sediments were pre-adapted to HCs as their community structure and diversity remained unchanged following HC addition. Conversely, HC addition significantly modified pristine sediment communities with selection of HC-degraders. These findings highlight the importance of understanding community assembly processes and can facilitate the prediction of microbial response to oil spills.
Supervisor: Witte, Ursula ; Anderson, James Arthur ; Gubry-Rangin, Cécile ; Gontikaki, Evina Sponsor: NERC ; BP ; Intertek
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Hydrocarbons ; Petroleum ; Biodegradation ; Oil pollution of the sea ; Oil spills