@article {9526,
	title = {Identification of microbial exopolymer producers in sandy and muddy intertidal sediments by compound-specific isotope analysis},
	journal = {Peer Community Journal},
	volume = {3},
	year = {2023},
	month = {Jan-01-2023},
	abstract = {Extracellular polymeric substances (EPS) refer to a wide variety of high molecular weight molecules secreted outside the cell membrane by biofilm microorganisms. In the present study, EPS from marine microphytobenthic biofilms were extracted and their isotope ratios were analysed. A comparison of these ratios with the carbon isotope ratios of fatty acid biomarkers allowed the identification of the main EPS producers of two contrasting types of intertidal marine sediments. Our study reveals that EPS sources are more diverse in sandy sediments than in muddy sediments. We also found distinct patterns in the production and breakdown of EPS in sandy and muddy environments. The main difference observed was in how epipelic and epipsammic diatoms affected the chemistry of EPS, which had significant implications for the growth of bacteria specialized in utilizing EPS. These differences were likely linked to variations in the functioning of epipelic and epipsammic communities, specifically in how EPS was used either for motility or for cell attachment.},
	doi = {10.24072/pcjournal.336},
	url = {https://peercommunityjournal.org/articles/10.24072/pcjournal.336/},
	author = {C{\'e}dric Hubas and Gaubert-Boussarie, Julie and D{\textquoteright}Hondt, An-Sofie and Bruno Jesus and Lamy, Dominique and Meleder, Vona and Prins, Antoine and Rosa, Philippe and Stock, Willem and Sabbe, Koen}
}
@article {8995,
	title = {The response of microphytobenthos to physical disturbance, herbicide, and titanium dioxide nanoparticle exposure},
	journal = {Marine Pollution Bulletin},
	volume = {185},
	year = {2022},
	month = {Jan-12-2022},
	pages = {114348},
	abstract = {The microphytobenthos that form transient biofilms are important primary producers in intertidal, depositional habitats, yet we have only a limited understanding of how they respond to the cumulative impacts of the growing range of anthropogenic stressors to which they are exposed. We know even less about how the temporal alignment of exposure {\textendash} such as duration and exposure sequence {\textendash} may affect the response. Estuarine biofilms were cultured in mesocosms and exposed to the herbicide glyphosate and titanium dioxide (TiO2) nanoparticles in different sequences (glyphosate-first or TiO2-first), as well as in the presence and absence of physical disturbance. We found that at environmentally realistic chemical concentrations, the order of exposure was less important than the total stressor scenario in terms of impacts on key functional attributes and diatom community structure. Physical disturbance did not have an impact on functional attributes, regardless of exposure sequence.},
	issn = {0025326X},
	doi = {10.1016/j.marpolbul.2022.114348},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0025326X2201030X},
	author = {Rimmer, James E.V. and C{\'e}dric Hubas and Wyness, Adam J. and Bruno Jesus and Hartley, Morgan and Blight, Andrew J. and Prins, Antoine and Paterson, David M}
}
@article {8249,
	title = {Photosynthesis from stolen chloroplasts can support sea slug reproductive fitness},
	journal = {Proceedings of the Royal Society B: Biological Sciences},
	volume = {288},
	year = {2021},
	month = {May-09-2023},
	abstract = {Some sea slugs are able to steal functional chloroplasts (kleptoplasts) from their algal food sources, but the role and relevance of photosynthesis to the animal host remain controversial. While some researchers claim that kleptoplasts are slowly digestible {\textquoteleft}snacks{\textquoteright}, others advocate that they enhance the overall fitness of sea slugs much more profoundly. Our analysis shows light-dependent incorporation of\&nbsp;13C and\&nbsp;15N in the albumen gland and gonadal follicles of the sea slug\&nbsp;Elysia timida, representing translocation of photosynthates to kleptoplast-free reproductive organs. Long-chain polyunsaturated fatty acids with reported roles in reproduction were produced in the sea slug cells using labelled precursors translocated from the kleptoplasts. Finally, we report reduced fecundity of\&nbsp;E. timida\&nbsp;by limiting kleptoplast photosynthesis. The present study indicates that photosynthesis enhances the reproductive fitness of kleptoplast-bearing sea slugs, confirming the biological relevance of this remarkable association between a metazoan and an algal-derived organelle.},
	issn = {0962-8452},
	doi = {10.1098/rspb.2021.1779},
	url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2021.1779},
	author = {Cartaxana, Paulo and Rey, Felisa and LeKieffre, Charlotte and Lopes, Diana and C{\'e}dric Hubas and Spangenberg, Jorge E. and Escrig, St{\'e}phane and Bruno Jesus and Calado, Gon{\c c}alo and Domingues, Ros{\'a}rio and K{\"u}hl, Michael and Calado, Ricardo and Meibom, Anders and Cruz, S{\'o}nia}
}
@article {6910,
	title = {Effect of Light Intensity and Light Quality on Diatom Behavioral and Physiological Photoprotection},
	journal = {Frontiers in Marine Science},
	volume = {7},
	year = {2020},
	pages = {203},
	abstract = {In this study, we investigated the different photoregulation responses of diatom dominated natural biofilms to different light intensities and wavelengths, over a tidal cycle in the laboratory. We compared the overall effect of light spectral quality from its light absorption (Qphar) dependent effect. Two different conditions were compared to study photoprotective strategies: sediment (migrational) and without sediment (non-migrational). Three different colors (blue, green, and red) and two light intensities (low light, LL at 210 μmol.photons.m<sup>{\textendash}2</sup>.s<sup>{\textendash}1</sup> and high light, HL at 800 μmol.photons.m<sup>{\textendash}2</sup>.s<sup>{\textendash}1</sup>) showed strong interactions in inducing behavioral and physiological photoprotection. Non-migrational biofilm non-photochemical quenching (NPQ) was much more reactive to blue HL than red HL while it did not differ in LL. We observed a biphasic NPQ response with a light threshold between 200 and 250 μmol.photons.m<sup>{\textendash}2</sup>.s<sup>{\textendash}1</sup> of Qphar that elicited the onset of physiological photoprotection. Similar HL differences were not observed in migrational biofilms due to active vertical migration movements that compensated light saturating effects. Our results showed that within migrational biofilms there was an interaction between light quality and light intensity on cell accumulation pattern at the sediment surface. This interaction led to inverse diatom accumulation patterns between blue and red light at the same intensity: LL (blue + 200.67\%, red + 123.96\%), HL (blue + 109.15\%, red + 150.34\%). These differences were largely related to the differential amount of light absorbed at different wavelengths and highlighted the importance of using wavelength standardized intensities. Different vertical migration patterns significantly affected the total pigment content measured at the surface, suggesting that cell could migrate downward more than 2 mm as a photoregulatory response. Colloidal carbohydrates patterns paralleled the vertical migration movements, highlighting their possible role in diatom motility. Our data strongly suggests a wavelength and Qphar dependent light stress threshold that triggers upward and downward movements to position microphytobenthic diatoms at their optimal depth.},
	issn = {2296-7745},
	doi = {10.3389/fmars.2020.00203},
	url = {https://www.frontiersin.org/article/10.3389/fmars.2020.00203},
	author = {Prins, Antoine and Deleris, Paul and C{\'e}dric Hubas and Bruno Jesus}
}
@article {7060,
	title = {Functional kleptoplasts intermediate incorporation of carbon and nitrogen in cells of the Sacoglossa sea slug Elysia viridis},
	journal = {Scientific Reports},
	volume = {10},
	year = {2020},
	month = {Jan-12-2020},
	abstract = {Some sacoglossan sea slugs incorporate intracellular functional algal chloroplasts, a process termed kleptoplasty. {\textquotedblleft}Stolen{\textquotedblright} chloroplasts (kleptoplasts) can remain photosynthetically active up to several months, contributing to animal nutrition. Whether this contribution occurs by means of translocation of photosynthesis-derived metabolites from functional kleptoplasts to the animal host or by simple digestion of such organelles remains controversial. Imaging of\&nbsp;13C and\&nbsp;15N assimilation over a 12-h incubation period of\&nbsp;Elysia viridis\&nbsp;sea slugs showed a light-dependent incorporation of carbon and nitrogen, observed first in digestive tubules and followed by a rapid accumulation into chloroplast-free organs. Furthermore, this work revealed the presence of\&nbsp;13C-labeled long-chain fatty acids (FA) typical of marine invertebrates, such as arachidonic (20:4n-6) and adrenic (22:4n-6) acids. The time frame and level of\&nbsp;13C- and\&nbsp;15N-labeling in chloroplast-free organs indicate that photosynthesis-derived primary metabolites were made available to the host through functional kleptoplasts. The presence of specific\&nbsp;13C-labeled long-chain FA, absent from\&nbsp;E. viridis\&nbsp;algal food, indicates animal based-elongation using kleptoplast-derived FA precursors. Finally, carbon and nitrogen were incorporated in organs and tissues involved in reproductive functions (albumin gland and gonadal follicles), implying a putative role of kleptoplast photosynthesis in the reproductive fitness of the animal host.},
	doi = {10.1038/s41598-020-66909-7},
	url = {http://www.nature.com/articles/s41598-020-66909-7},
	author = {Cruz, S{\'o}nia and LeKieffre, Charlotte and Cartaxana, Paulo and C{\'e}dric Hubas and Najet Thiney and Jakobsen, Sofie and Escrig, St{\'e}phane and Bruno Jesus and K{\"u}hl, Michael and Calado, Ricardo and Meibom, Anders}
}
@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}
}
