Molecular microbial ecology of contaminated marine sediment near Casey Station, Antarctica
The Antarctic marine environment is a beautiful and productive yet fragile and sensitive ecosystem. In areas close to research stations, there is evidence of the impact of human activities in the form of petroleum and heavy-metal contamination. The process of biodegradation by microbes is a major pa...
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| Format: | Thesis |
| Language: | English |
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2004
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| Online Access: | https://eprints.utas.edu.au/21264/ https://eprints.utas.edu.au/21264/1/whole_PowellShane2004_thesis.pdf |
| Summary: | The Antarctic marine environment is a beautiful and productive yet fragile and sensitive ecosystem. In areas close to research stations, there is evidence of the impact of human activities in the form of petroleum and heavy-metal contamination. The process of biodegradation by microbes is a major pathway for the removal of some of these contaminants from the environment. It is therefore important to understand the response of microbial communities to pollution. In this study, molecular techniques were used to investigate the microbial ecology of impacted and non-impacted marine sediments near Casey Station, Antarctica. Initially, a study of the microbial diversity in an impacted and non-impacted bay showed that the two bays had diverse but not significantly different communities. 16S rRNA gene clone libraries revealed the presence of similar species to those found in other cold marine sediments. However, there was a cluster of clones related to the hydrocarbon-utilising sulfate-reducing genus Desulfobacula that was found only in the impacted site. Further investigation using real-time PCR discovered that they were also present in the non-impacted site, but in significantly smaller numbers. Denaturing gradient gel electrophoresis (DGGE) was used in a nested-design survey of two impacted and two non-impacted locations. There were significant differences both within and between locations. The microbial community structure within impacted locations was more variable than in control locations and correlations with environmental variables showed that pollution was one of a number of factors influencing the microbial communities. In a separate field experiment, a mixture of oils was shown to affect the development of microbial communities. An in situ experiment to investigate the short-term effects of four different oils was conducted at one of the control sites. A polyphasic approach involving microscopic cell counts, most probable number counts and DGGE was used to analyse the microbial communities. It was found that special Antarctic blend diesel (SAB), a lubricant(Mobil OW40) and the same lubricant after use in a vehicle all had a significant effect on the microbial community when compared to a control treatment. The microbial community in sediment exposed to a biodegradable lubricant (Titan GT1) however was not significantly different to that of the control. Finally, the biodegradation of nonane, one of the components of SAB, was measured in enrichment cultures developed from sediment exposed to SAB. Sequencing of two DGGE bands from the enrichment culture revealed the presence of pseudomonas- and Colwellia-like species. |
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