Community Composition of a Hypersaline Endoevaporitic Microbial Mat

Abstract

A hypersaline, endoevaporitic microbial community in Eilat, Israel, was studied by microscopy and by PCR amplification of genes for 16S rRNA from different layers. In terms of biomass, the oxygenic layers of the community were dominated by Cyanobacteria of the Halothece, Spirulina, and Phormidium types, but cell counts (based on 4,6-diamidino-2-phenylindole staining) and molecular surveys (clone libraries of PCR-amplified genes for 16S rRNA) showed that oxygenic phototrophs were outnumbered by the other constituents of the community, including chemotrophs and anoxygenic phototrophs. Bacterial clone libraries were dominated by phylotypes affiliated with the Bacteroidetes group and both photo-and chemotrophic groups of ␣-proteobacteria. Green filaments related to the Chloroflexi were less abundant than reported from hypersaline microbial mats growing at lower salinities and were only detected in the deepest part of the anoxygenic phototrophic zone. Also detected were nonphototrophic ␥-and ␦-proteobacteria, Planctomycetes, the TM6 group, Firmicutes, and Spirochetes. Several of the phylotypes showed a distinct vertical distribution in the crust, suggesting specific adaptations to the presence or absence of oxygen and light. Archaea were less abundant than Bacteria, their diversity was lower, and the community was less stratified. Detected archaeal groups included organisms affiliated with the Methanosarcinales, the Halobacteriales, and uncultured groups of Euryarchaeota.

From community approaches to single-cell genomics: the discovery of ubiquitous hyperhalophilic Bacteroidetes generalists

“…For instance, Hqr. walsbyi cultured strains have o1.8% divergence in their 16S rRNA gene sequences (Legault et al, 2006) while environmental phylotypes recovered from highly distant saltern ponds in Spain Legault et al, 2006), Israel (Soerensen et al, 2005), Turkey (Mutlu et al, 2008), Tunisia (Baati et al, 2008), Peru (Maturrano et al, 2006) and Australia (Oh et al, 2010) normally present o1% divergence. In contrast, some Haloquadratum sequences recovered in this work (Table 2 and Figure 2) showed a higher divergence (up to 5%) in the analyzed 16S rRNA gene fragment.…”

Micron-scale mapping of sulfur cycling across the oxycline of a cyanobacterial mat: a paired nanoSIMS and CARD-FISH approach

“…Previous work has shown that sulfur-cycling organisms form a major metabolic and phylogenetic component of microbial mats in Guerrero Negro and similar environments (Canfield and Des Marais, 1993;Jorgensen, 1994;Risatti et al, 1994;Krekeler et al, 1997;Teske et al, 1998;Minz et al, 1999a,b;Spear et al, 2003;Sorensen et al, 2005;Ley et al, 2006). Whole-cell FISH surveys of microbial assemblages within the mat, focusing on sulfate reducers and other known monophyletic sulfur-metabolizing guilds, allow for micron-scale mapping of the spatial distribution of these organisms (for example, Minz et al, 1999a;Wieland et al, 2003;Tonolla et al, 2005;Baumgartner et al, 2006).…”

New cell extraction procedure applied to deep subsurface sediments

“…These active (Biddle et al 2006;Schippers et al 2005) and diverse (Inagaki et al 2006;Kormas et al 2003;Sørensen et al 2006) communities of Bacteria and Archaea have been shown to exist at depths as great as 800 meters below the seafloor (mbsf) (Parkes et al 2000;Zink et al 2003) and potentially exist deeper. Recent studies have shown that the microbial communities in subsurface environments are more physiologically and phylogenetically complex than previously thought (Amend and Teske 2005;D'Hondt et al 2004) and play an important role in biogeochemical cycles (D'Hondt et al 2002;Parkes et al 1994).…”