Diversity and function in microbial mats from the Lucky Strike hydrothermal vent field

Abstract

Diversity and function in microbial mats from the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge) were investigated using molecular approaches. DNA and RNA were extracted from mat samples overlaying hydrothermal deposits and Bathymodiolus azoricus mussel assemblages. We constructed and analyzed libraries of 16S rRNA gene sequences and sequences of functional genes involved in autotrophic carbon fixation [forms I and II RuBisCO (cbbL/M), ATP-citrate lyase B (aclB)]; methane oxidation [particulate methane monooxygenase (pmoA)] and sulfur oxidation [adenosine-5 0 -phosphosulfate reductase (aprA) and soxB]. To gain new insights into the relationships between mats and mussels, we also used new domain-specific 16S rRNA gene primers targeting Bathymodiolus sp. symbionts. All identified archaeal sequences were affiliated with a single group: the marine group 1 Thaumarchaeota. In contrast, analyses of bacterial sequences revealed much higher diversity, although two phyla Proteobacteria and Bacteroidetes were largely dominant. The 16S rRNA gene sequence library revealed that species affiliated to Beggiatoa Gammaproteobacteria were the dominant active population. Analyses of DNA and RNA functional gene libraries revealed a diverse and active chemolithoautotrophic population. Most of these sequences were affiliated with Gammaproteobacteria, including hydrothermal fauna symbionts, Thiotrichales and Methylococcales. PCR and reverse transcription-PCR using 16S rRNA gene primers targeted to Bathymodiolus sp. symbionts revealed sequences affiliated with both methanotrophic and thiotrophic endosymbionts.

Cutting through the smoke: the diversity of microorganisms in deep-sea hydrothermal plumes

“…Our results strongly indicate that the microbial community compositions at our sampling locations were related to the presence of reducing chemical species in the environment in line with previous research on the drivers of microbial assemblages and dispersion close to vent locations [3,7,37,39]. The taxa of the microbial assemblages described in this study are well documented at hydrothermal vent and other deep-sea environments [6,17,56–60]. As has been shown previously, most of them are common deep-sea bacteria, such as Halomonas and Marinobacter mixed with abundant Epsilonproteobacteria such as Arcobacter , Sulfurimonas and Caminibacter .…”

Biological data extraction from imagery – How far can we go? A case study from the Mid-Atlantic Ridge

“…On Eiffel Tower, large areas covered by mussels are matfree while other B. azoricus assemblages are completely covered (Cuvelier et al, 2009). A study by Crépeau et al (2011) showed a highly diverse microbial community within the microbial mats at Lucky Strike, covering hydrothermal deposits and B. azoricus individuals. While the relationships between mussels and mats are still poorly understood, it does not appear to point to a negative one as mussel assemblages covered by microbial mats coexist with mussel assemblages free of microbial mats, both of them being healthy.…”

“…While the relationships between mussels and mats are still poorly understood, it does not appear to point to a negative one as mussel assemblages covered by microbial mats coexist with mussel assemblages free of microbial mats, both of them being healthy. A commensal relationship thus appears to be the most convincing scenario in which sulphur and methane oxidizers benefit from fluid dispersion by mussels and numerous heterotrophic microorganisms degrade the organic material released by the mussels (Crépeau et al, 2011).…”

Microbial diversity and adaptation to high hydrostatic pressure in deep-sea hydrothermal vents prokaryotes

“…The Bacteria domain is dominated by Epsilonproteobacteria detected in hydrothermal fluids, in sea water, hydrothermal sediments, microbial mats and in association with macrofauna (Reysenbach et al 2000(Reysenbach et al , 2002Alain et al 2002b;Teske et al 2002;Huber et al 2003;Page et al 2004;Suzuki et al 2005;Campbell et al 2006;Gerasimchuk et al 2010;Crépeau et al 2011;Sylvan et al 2012); other bacterial groups were also detected, such as Alpha-, Beta-, Delta and Gammaproteobacteria, Aquificales, Desulfobacteriales, Thermotogales, Deinococcus-Thermus, Deferribacteres, Firmicutes, CFB (Cytophaga-Flavobacteria-Bacteroidetes), Acidobacteria, Verrumicrobia and Planctomycetes (Alain et al 2002a;Reysenbach et al 2002;Teske et al 2002;Huber et al 2003;Page et al 2004;Cré-peau et al 2011;Orcutt et al 2011;Sylvan et al 2012). More than one hundred species of Bacteria (17 phyla, 72 genera, 113 species) and Archaea (3 phyla, 17 genera and 62 species) were isolated and cultured from deep-sea hydrothermal vents, mainly from the Pacific ocean (69-77 % of species) and, in lesser numbers, from the Atlantic (19-28 % of species) and Indian (2-4 % of species) Oceans.…”