Linking the degradation of model saturated and aromatic crude oil components to specific marine microbial taxa during biostimulation and bioaugmentation using RNA-stable isotope probing

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Copyright: Taleb, Iman
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Abstract
In an effort to dissipate the notorious effect of the catastrophic oil spills that occur in the marine environment, several bioremediation techniques have been developed with variable outcomes depending on several environmental and nutritional factors. With the high level of sophistication in the development of molecular techniques, and their application in bioremediation, it has become possible to identify key hydrocarbon-degrading marine bacteria responsible for the degradation of specific hydrocarbon compounds. However, only recently, studies that linked the degradation of hydrocarbons to specific marine phyla have started to emerge. The present study applied RNA-stable isotope probing in order to identify key marine hydrocarbonoclastic bacteria acquiring carbon from model oil hydrocarbons (hexadecane, benzene and naphthalene) under biostimulation and natural attenuation conditions in pristine as well as in oil pre-adapted seawater in laboratory microcosms. Pre-adaptation of seawater to oil induced the degradation of benzene, but slowed down the degradation of naphthalene and hexadecane. DGGE analysis showed high selection towards specific hydrocarbon degrading lineages that dominated the community profiles. The effect of a new concept in bioremediation, autochthonous bioaugmentation, on the selected hydrocarbons in the presence or absence of nutrients was also investigated using hydrocarbon degrading isolates obtained from seawater. Bioaugmented cultures showed more rapid degradation of all compounds with variability in the extent of degradation per compound and nutritional conditions. Another highlight of the present study was the first application of RNA-SIP during autochthonous bioaugmentation in order to determine the fate of the labelled carbon isotopes. Profiling of the community showed that hexadecane was degraded mainly by the added Rhodococcus qingshangii, while benzene was not degraded by the added Alteromonas addita, but by members of the native community. Carbon from naphthalene, however, was consumed by the added Pseudomonas alcaliphila as well as by another indigenous taxon. This thesis assigned the degradation of selected hydrocarbons to novel putative hydrocarbonoclastic bacteria and highlighted some of the microbial interactions during bioremediation, which provided new insights for further developments of the promising autochthonous bioaugmentation strategy.
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Taleb, Iman
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2014
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Thesis
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PhD Doctorate
UNSW Faculty
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