INVESTIGADORES
MARCOS magali Silvina
congresos y reuniones científicas
Título:
Bacterial Communities and Hydrocarbon-degrading Populations in Polluted Sediments from Two Biogeographic Regions of Patagonia
Autor/es:
MARCOS, M. S.; GUIBERT, L. M.; COMMENDATORE, M. G.; LOZADA, M.; DIONISI, H. M.
Lugar:
Mar del Plata
Reunión:
Congreso; VIII Congreso Argentino de MicrobiologIa General; 2012
Resumen:
Coastal sediments hold a great diversity of microorganisms, which play an essential role in marine ecosystem processes. In-depth studies of microbial communities are essential to understand their functioning, as well as the effect of anthropogenic impacts on community structure, function and microbial services. The aim of this study was to characterize bacterial communities that inhabit hydrocarbon-polluted intertidal sediments from North-Central (NCP) and South Patagonia (SP), with emphasis in hydrocarbon-degrading bacteria.  Composite intertidal sediment samples were retrieved at two hydrocarbon-polluted sites in fall of 2008: Cordova Cove (NCP) is mainly polluted with crude oil (samples CC08-1 and CC08-2) and Orion Plant, located in Ushuaia Bay (SP), is mainly polluted with oil-refined products (sample OR08). In addition sample PF08, collected at Valdes Peninsula (NCP), was used as a non-polluted control site. Pyrosequencing of the V4 hypervariable region of 16S rRNA genes from Bacteria resulted in approximately 100,000 reads from the four sediment samples. Coverage values ranged from 82.6 to 88.1%. CC08-2 showed the highest richness and diversity, with almost 3,900 and 7,600 observed and estimated OTUs, respectively (defined at 97% sequence identity). Richness and diversity decreased in the following order: CC08-2 > PF08 > CC08-1 > OR08. Accordingly, OR08 and CC08-1 showed the highest species dominance, followed by PF08 and CC08-2. In sample CC08-1, Psychromonas and Vibrio were highly abundant, representing 16.1% and 2.4% of the reads, respectively. These genera are facultative anaerobe microorganisms that have been linked to hydrocarbon biodegradation, which was in agreement with the nature of this sediment sample (high organic matter content including hydrocarbons, low oxygen content and fine granulometry). On the other hand, OR08 showed the presence of various evenly distributed genera associated with hydrocarbon degradation, including: Sulfitobacter (1.4%), Glaciecola (2.1%), Marinobacter (1.2%), Oleispira (2.9%), Nocardioides (1.9%), Pseudoalteromonas (2.4%) and Psychrobacter (1.3%). In CC08-2, sequences assigned to the Glaciecola genus represented 1.2% of the reads. In addition, members of other taxonomic families known to contain hydrocarbon degraders were detected in this sample, although sequences could not be classified at the genus level, suggesting the presence of yet undescribed hydrocarbon-degrading bacterial populations. On the other hand, most genera for which hydrocarbon degrading organisms were described were found at low abundances in the non-polluted site. The high heterogeneity of the bacterial communities from polluted sediments of Patagonia highlight the importance of the local environmental conditions and the presence of microniches in the structuring of the bacterial communities.