Lipid biomarker and phylogenetic analyses to reveal archaeal biodiversity and distribution in hypersaline microbial mat and underlying sediment

Abstract

This study has utilized the tools of lipid biomarker chemistry and molecular phylogenetic analyses to assess the archaeal contribution to diversity and abundance within a microbial mat and underlying sediment from a hypersaline lagoon in Baja California. Based on abundance of ether-linked isoprenoids, archaea made up from 1 to 4% of the cell numbers throughout the upper 100 mm of mat and sediment core. Below this depth archaeal lipid was two times more abundant than bacterial. Archaeol was the primary archaeal lipid in all layers. Relatively small amounts of caldarchaeol (dibiphytanyl glyceroltetraether) were present at most depths with phytanyl to biphytanyl molar ratios lowest (approximately 10 : 1) in the 4-17 mm and 100-130 mm horizons, and highest (132 : 1) in the surface 0-2 mm. Lipids with cyclic biphytanyl cores were only detected below 100 mm. A novel polar lipid containing a C(30) isoprenoid (squalane) moiety was isolated from the upper anoxic portion of the core and partially characterized. Hydrocarbon biomarker lipids included pentamethylicosane (2-10 mm) and crocetane (primarily below 10 mm). Archaeal molecular diversity varied somewhat with depth. With the exception of samples at 0-2 mm and 35-65 mm, Thermoplasmatales of marine benthic group D dominated clone libraries. A significant number of phylotypes representing the Crenarchaeota from marine benthic group B were generally present below 17 mm and dominated the 35-65 mm sample. Halobacteriaceae family made up 80% of the clone library of the surface 2 mm, and consisted primarily of sequences affiliated with the haloalkaliphilic Natronomonas pharaonis.

Quantitative and phylogenetic study of the Deep Sea Archaeal Group in sediments of the Arctic mid-ocean spreading ridge

“…DSAG, high throughput 454 amplicon sequences from our previous study (Jorgensen et al, 2012) were clustered into 18 OTUs (97% cut-off) and added to the tree using the parsimony tool in the ARB work package and their positions are marked in Figure 3. We note that more than 60% of all published sequences in the Silva database (SSUref 111) originated from a single habitat, the hypersaline ponds, Guerrero Negro in Baja California, Mexico (Ley et al, 2006; Jahnke et al, 2008; Robertson et al, 2009). Further, we identified a fourth cluster of sequences designated DSAG in the Silva database.…”

The effect of sulfate concentration on (sub)millimeter-scale sulfide δ34S in hypersaline cyanobacterial mats over the diurnal cycle

“…The surface photosynthetic layers and underlying chemocline represent the most dynamic and productive horizons of the microbial mat, supporting high levels of microbial diversity and biomass relative to permanently anoxic underlying layers (Ley et al, 2006;Jahnke et al, 2008). This $3-4 mm zone is also defined by steep photosynthetically controlled redox gradients and elevated rates of microbial activity, including some of the highest levels of bacterial sulfate reduction on record (Visscher et al, 1992;Canfield and Des Marais, 1993;Baumgartner et al, 2006;Dillon et al, 2007).…”

“…This system has been well characterized for its bulk microbiological community structure (Risatti et al, 1994;Spear et al, 2003;Ley et al, 2006;Green et al, 2008;Jahnke et al, 2008;Kunin et al, 2008;Orphan et al, 2008;Robertson et al, 2009), large-scale sulfur cycling (Canfield and Des Marais, 1993;Jorgensen, 1994), and the diurnal variations that arise from photosynthetic redox changes (Canfield and Des Marais, 1993;Jorgensen, 1994;Visscher et al, 2003;Decker et al, 2005). These Microcoleus-dominated mats support active aerotolerant sulfate reducers in the photosynthetically-active uppermost few mm as well as anerobic sulfate reduction in the permanently anoxic zones beneath the chemocline (Canfield and Des Marais, 1993).…”

Biogeochemistry of intertidal microbial mats from Qatar: New insights from organic matter characterisation

“…8g); it is a DAGE comprising two C 20 isoprenoid alkyl chains, and is derived from, and widespread in, Archaea (DeRosa and Gambacorta, 1988). As such, it has been found in diverse settings, including geothermal sinters (Pancost et al, 2005(Pancost et al, , 2006Kaur et al, 2015), microbial mats (Bühring et al, 2009), hypersaline settings (Jahnke et al, 2008;Bray et al, 2012), cold seep sediments (e.g. Hinrichs et al, 2000;Pancost et al, 2001;Zhang et al, 2003) and peats (Pancost et al, 2011;Zheng et al, 2014).…”