POLLUTED MARINE ECOSYSTEMS: RESERVOIR OF MICROBIAL RESOURCES FOR HYDROCARBON BIOREMEDIATION
Tesi di Dottorato
Data di Pubblicazione:
2014
Citazione:
POLLUTED MARINE ECOSYSTEMS: RESERVOIR OF MICROBIAL RESOURCES FOR HYDROCARBON BIOREMEDIATION / M. Barbato ; coordinatore: D. Daffonchio ; supervisor: D. Daffonchio. DIPARTIMENTO DI SCIENZE PER GLI ALIMENTI, LA NUTRIZIONE E L'AMBIENTE, 2014 Dec 18. 27. ciclo, Anno Accademico 2014. [10.13130/barbato-marta_phd2014-12-18].
Abstract:
Hydrocarbon (HC) pollution is a worldwide threat to marine natural ecosystems due to the increasing exploitation of underground marine petroleum deposits in several areas and to the high traffic of oil tankers and the presence of submarine pipes that are main transport routes for crude oil and refined products. HCs spread in the marine environment is mainly due to accidental oil spills or inadequate practices and their release affects marine ecosystems causing severe ecological and economical damages. The Mediterranean Sea is particularly endangered by hydrocarbon pollution because of its physical nature – it is an enclosed basin with a slow water exchange – and because it hosts about 20% of the global oil tanker traffic in its waters and tens of oil-related sites along its coastline. The conventional remediation strategies, comprising chemical and physical methods, are extremely expensive and invasive, therefore the development of cheaper and eco-friendly approaches is crucial to preserve human and ecosystem health. In this perspective, bioremediation (i.e. the use of living organisms to remove pollutants from a contaminated area) is a promising technology which, taking advantage of microbes’ metabolic potential to degrade a wide range of pollutants, can both reduce the costs and may represent a permanent solution. Nevertheless, there is still a scarce knowledge of the processes and the microorganisms involved in the clean-up of hydrocarbons from marine environments, hence some problems still exist concerning the in-field application of bioremediation.
The aim of the present PhD thesis was to: i) investigate the overall prokaryotic diversity of pristine and oil polluted sites across the whole Mediterranean Sea; ii) depict the phylogenetic and functional diversity of hydrocarbonoclastic bacteria inhabiting pristine and polluted sites; iii) establish a large collection of bacteria showing degrading activities toward hydrocarbon compounds; iv) set up microcosm experiments to investigate the potential of bacterial bioaugmentation in bioremediation processes under laboratory scale conditions, v) test the degrading potential of selected bacterial strains and consortia under different pressure values, simulating different depths along the water column.
The diversity of planktonic bacterial communities in the Mediterranean Sea was firstly evaluated on open seawater samples collected at different depths in a transect covering the main oil tanker route across the whole basin, from the Levantine Sea to the Gibraltar strait. Automated Ribosomal Intergenic Spacer Analysis (ARISA) showed that the microbiome inhabiting deep and surface water samples were sharply separated. Furthermore, the composition of the bacterial communities described in the surface layers of the water columns at different sampling stations has been significantly correlated, beside to their geographical position and depth, to the temperature and salinity values recorded for each sample.
Denaturing Gradient Gel Electrophoresis (DGGE) and ARISA fingerprinting were also applied to depict the bacterial composition of highly polluted sediments collected at the Ancona harbor (Italy) and El-Max district (Egypt), showing the significant influence of the different pollutants’ concentration (i.e. hydrocarbons, heavy metals) in the selection of peculiar bacterial assemblages . This molecular approach led to the identification of bacterial species potentially useful for site-tailored bioremediation purposes. A large collection of hydrocarbon degrading bacterial strains was hence established from enrichments using contaminated sediments as inoculum and diesel, crude oil and naphthalene as unique carbon sources. The cultivation approaches adopted to enrich and isolate hydroc
Tipologia IRIS:
Tesi di dottorato
Keywords:
bioremediation; Mediterranean Sea; bacterial communities; hydrocarbons; marine pollution
Elenco autori:
M. Barbato
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