Data/hora: 09/06/2024 10:32:52

Provedor de dados: 	5	
País: 	France	
Título: 	Potentiels physiologiques et métaboliques de communautés microbiennes de sédiments de subsurface : approches culturale, génomique et métagénomique	
Autores: 	Gaboyer, Frédéric.	
Data: 	2014-09-18	
Ano: 	2014	
Palavras-chave: 	Métagénomes; Ecologie microbienne; Environnements extrêmes; Subsurface; Adaptation microbienne; Evolution microbienne; Physiologie microbienne; Génomes; Metagenomes; Genomes; Microbial physiology; Microbial evolution; Microbial adaptation; Subsurface; Extreme environments; Microbial ecology.	
Resumo: 	Microbial communities inhabiting marine subsurface sediments were described up to 1922 mbsf (meters below the sea floor) andcould represent 0.6% of the total biomass. This microbial diversity, remaining elusive to cultivation, comprises groups specific to subsurface environments and groups of generalists found in contrasted habitats, all belonging to the 3 domains of life (Bacteria,Eukarya and Archaea). Although playing a major role in global geochemical cycles, the microbial ecology of the subseafloor remains largely unknown. The hostile conditions of subsurface sediments contrast with the descriptions of microbial activity andviability in the subseafloor. In this context, many questions related to the microbial physiology and the lifestyles of buried communities remain to be answered. The objective of this thesis was to better understand which adaptive strategies could be deployed by subseafloor microbial communities and to characterize their physiological potential. In that aim, 3 approaches were used.(1) A cultural approach enabled describing 2 novel sedimentary bacterial species (Halomonas lionensis, a versatile generalist and Phaeobacter leonis a typical marine bacterium). The survival of these 2 species to subseafloor conditions and of the subsurface bacteria Sunxiuqinia faeciviva, isolated at 247 mbsf, was then studied. (2) Using a structural and comparative genomic approach, the physiological plasticity of H. lionensis was investigated. (3) Finally, the functional potential of the microbial communities buried at 31 and 136 mbsf in the Canterbury Basin was analyzed, by studying the 2 corresponding metagenomes. Cultural and genomics results showed that H. lionensis and S. faeciviva are more resistant to subsurface constrains than P. leonis and, in the case of H. lionensis, this may involve various physiological properties, maybe explaining thee cological success of the genus Halomonas. Metagenomic data showed that the functional and the phylogenetic diversity of the subseafloor are distinct from the ones from surface environments and highlighted the importance of metabolic pathways like fermentation, methanogenesis and β-oxidation. Genes of ecological and evolutionary interests enabled speculating about lifestyles of buried microorganisms and analyses of genomic fragments highlighted recombination events of still uncultivated microbial groups	
Tipo: 	Text	
Idioma: 	Francês	
Identificador: 	https://archimer.ifremer.fr/doc/00609/72134/70886.pdf

https://archimer.ifremer.fr/doc/00609/72134/	
Editor: 	Ecole Doctorale des Sciences de la Mer	
Formato: 	application/pdf	
Fonte: 	info:eu-repo/semantics/openAccess

restricted use