@article {5153,
	title = {{A nanoscale study of carbon and nitrogen fluxes in mats of purple sulfur bacteria: implications for carbon cycling at the surface of coastal sediments}},
	journal = {Frontiers in Microbiology},
	volume = {8},
	year = {2017},
	pages = {1995},
	abstract = {<p>Mass blooms of purple sulfur bacteria growing seasonally on green stranded macroalgae have a major impact on the microbial composition and functionality of intertidal mats. To explore the active anoxygenic phototrophic community in purple bacterial mats from the Roscoff Aber Bay (Brittany, France), we conducted a combined approach including molecular and high-resolution secondary ion mass spectrometry (NanoSIMS) analyses. To investigate the dynamics of carbon and nitrogen assimilation activities, NanoSIMS was coupled with a stable isotope probing (SIP) experiment and a compound specific isotope analysis (CSIA) of fatty acid methyl ester (FAME). Sediment samples were incubated with 13C- and/or 15N-labelled acetate, pyruvate, bicarbonate and ammonium. NanoSIMS analysis of 13C - and 15N -incubated samples showed elevated incorporations of 13C - and 15N in the light and of 13C -acetate in the dark into dense populations of spherical cells that unambiguously dominated the mats. These results confirmed CSIA data that ranked vaccenic acid, an unambiguous marker of purple sulfur bacteria, as the most strongly enriched in the light after 13C -acetate amendment and indicated that acetate uptake, the most active in the mat, was not light-dependent. Analysis of DNA- and cDNA-derived pufM gene sequences revealed that Thiohalocapsa-related clones dominated both libraries and were the most photosynthetically active members of the mat samples. This study provides novel insights into the contribution of purple sulfur bacteria to the carbon cycle during their seasonal developments at the sediment surface in the intertidal zone.</p>
},
	doi = {10.3389/fmicb.2017.01995},
	url = {https://www.frontiersin.org/articles/10.3389/fmicb.2017.01995/abstract},
	author = {C{\'e}dric Hubas and Boeuf, Dominique and Bruno Jesus and Najet Thiney and Bozec, Yann and Christian Jeanthon}
}
@article {3383,
	title = {Seasonal variations of the composition of microbial biofilms in sandy tidal flats: Focus of fatty acids, pigments and exopolymers},
	journal = {Estuarine, Coastal and Shelf Science},
	volume = {153},
	year = {2015},
	pages = {29 - 37},
	abstract = {<p>Abstract Biofilms, or microbial mats, are common associations of microorganisms in tidal flats; they generally consist of a large diversity of organisms embedded in a matrix of Extracellular Polymeric Substances (EPS). These molecules are mainly composed of carbohydrates and proteins, but their detailed monomer compositions and seasonal variations are currently unknown. Yet this composition determines the numerous roles of biofilms in these systems. This study investigated the changes in composition of carbohydrates in intertidal microbial mats over a year to decipher seasonal variations in biofilms and in varying hydrodynamic conditions. This work also aimed to assess how these compositions are related to microbial assemblages. In this context, natural biofilms whose development was influenced or not by artificial structures mimicking polychaete tubes were sampled monthly for over a year in intertidal flats of the Chausey archipelago. Biofilms were compared through the analysis of their fatty acid and pigment contents, and the monosaccharide composition of their \{EPS\} carbohydrates. Carbohydrates from both colloidal and bound \{EPS\} contained mainly glucose and, to a lower extent, galactose and mannose but they showed significant differences in their detailed monosaccharide compositions. These two fractions displayed different seasonal evolution, even if glucose accumulated in both fractions in summer; bound \{EPS\} only were affected by artificial biogenic structures. Sediment composition in fatty acids and pigments showed that microbial communities were dominated by diatoms and heterotrophic bacteria. Their relative proportions, as well as those of other groups like cryptophytes, changed between times and treatments. The changes in \{EPS\} composition were not fully explained by modifications of microbial assemblages but also depended on the processes taking place in sediments and on environmental conditions. These variations of \{EPS\} compositions are likely to alter different ecosystem processes such as biostabilisation or pollutants trapping.</p>
},
	keywords = {biofilms, biogenic structures, EPS, fatty acids, monosaccharide composition, pigments},
	issn = {0272-7714},
	doi = {http://dx.doi.org/10.1016/j.ecss.2014.11.013},
	url = {http://www.sciencedirect.com/science/article/pii/S0272771414003412},
	author = {Passarelli, C and Tarik Meziane and Najet Thiney and Dominique Boeuf and B Jesus and Mickael Ruivo and Christian Jeanthon and C{\'e}dric Hubas}
}
