@article {McKay2012,
	title = {{Spatial heterogeneity and underlying geochemistry of phylogenetically diverse orange and white Beggiatoa mats in Guaymas Basin hydrothermal sediments}},
	journal = {Deep-Sea Research. Part I: Oceanographic Research Papers},
	volume = {67},
	year = {2012},
	pages = {21{\textendash}31},
	abstract = {Sulfide-oxidizing bacteria of the genus Beggiatoa are found in conspicuous, colorful mats on the seafloor above active hydrothermal seeps at Guaymas Basin. Guaymas Beggiatoa filaments fall into discrete size classes representing at least five separate 16S rRNA phylotypes, and appear either white, yellow, or orange. During two R/V Atlantis cruises to Guaymas Basin, 78 temperature profiles were taken near and within 15 different orange and white Beggiatoa mats by the Alvin submersible to investigate spatial relationships between mat color and hydrothermal fluid seeps, as indicated by elevated temperatures. The surface temperatures from 78 profiles are similar to each other (on average 8{\textendash}12~{\textdegree}C, warmer than bare sediments at 3{\textendash}4~{\textdegree}C), indicating that Guaymas Basin Beggiatoa spp., although relying on the hydrothermal system for energy and carbon sources, live within a relatively cool temperature range. Temperatures from 40~cm below orange Beggiatoa versus white Beggiatoa are the same, at 84~{\textdegree}C averaged across all mat systems. However, within a single mat system, temperatures are higher beneath the predominantly orange center of the mat than beneath the white mat periphery. Push core transects across the orange-to-white color change of three Beggiatoa mats showed stronger upward compression of isotherms and metabolic zones beneath the orange mat center than beneath white mat periphery. Hydrothermal temperature gradients push the microbial processes generating carbon and energy sources for Beggiatoa mats towards the sediment surface. The resulting steep gradients of hydrothermal electron donors and carbon sources to the sediment surface, rather than the in situ temperature by itself, control the relative positioning of orange and white filaments within a Guaymas Basin Beggiatoa mat. Given the wide spectrum of temperature and hydrothermal flux regimes between different mats, the orange/white pattern represents a relative preference or even a competitive balance among different Beggiatoa types that establishes itself within each hydrothermal hot spot.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	doi = {10.1016/j.dsr.2012.04.011},
	url = {http://dx.doi.org/10.1016/j.dsr.2012.04.011},
	author = {McKay, L J and MacGregor, B J and Biddle, J F and Albert, D B and Mendlovitz, H P and Hoer, D R and Lipp, J S and Lloyd, K G and Teske, A P}
}
@article {Kellermann2012,
	title = {{Symbiont{\textendash}host relationships in chemosynthetic mussels: A comprehensive lipid biomarker study}},
	journal = {Organic Geochemistry},
	volume = {43},
	year = {2012},
	pages = {112{\textendash}124},
	abstract = {Symbiosis with chemosynthetic microorganisms allows invertebrates from hydrothermal vents and cold seeps, such as mussels, snails and tubeworms, to gain nutrition independently of organic input from photosynthetic communities. Lipid biomarkers and their compound specific stable carbon isotopes ($δ$13C) have greatly aided the elucidation of chemosynthetic symbiosis. Due to recent methodological advances in liquid chromatography it is now possible to obtain a more holistic view of lipid biomarkers, including the analysis of intact polar membrane lipids (IPLs) and bacteriohopanepolyols (BHPs). This study provides an extensive examination of polar and apolar lipids in combination with stable carbon isotope analysis of three Bathymodiolus mussels (Bathymodiolus childressi, Bathymodiolus cf. thermophilus, Bathymodiolus brooksi) hosting different types of bacterial symbiont (methane-oxidizing, sulfur-oxidizing and a dual symbiosis with methane- and sulfur-oxidizing symbionts, respectively). We propose that IPLs with C16:1 acyl side chains, and phosphatidylglycerol (PG), diphosphatidylglycerol (DPG) and phosphatidylethanolamine (PE) head groups, which were only detected in the gill tissue, can be used as symbiont-characteristic biomarkers. These putative symbiont-specific IPLs provide the opportunity to detect and quantify the methanotrophic and thiotrophic symbionts within the gill tissue. Additional characteristic markers for methanotrophic symbionts were found in B. childressi and B. brooksi, including the BHP derivatives aminotriol and aminotetrol, 4-methyl sterols and diagnostic fatty acids (FAs), such as C16:1${\o}mega$9, C16:1${\o}mega$8, and C18:1${\o}mega$8. In general, the $δ$13C values of FAs, alcohols and BHP-derived hopanols were in accordance with carbon assimilation pathways of the respective methanotrophic or thiotrophic symbionts in all three Bathymodiolus mussels. Differences in BHP distribution as well as $δ$13C values in the two mussels hosting a methanotrophic symbiont may indicate the presence of different methanotrophic symbionts and/or changes in the nutritional status. In all three mussel species the $δ$13C values of lipid biomarkers assigned to the symbionts were similar to those of the hosts, indicating the importance of the bacterial symbionts as the main carbon source for the mussel tissue.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0146-6380},
	doi = {10.1016/j.orggeochem.2011.10.005},
	url = {http://dx.doi.org/10.1016/j.orggeochem.2011.10.005},
	author = {Kellermann, M Y and Schubotz, F and Elvert, M and Lipp, J S and Birgel, D and Prieto-Mollar, X and Dubilier, N and Hinrichs, K -U}
}
