Short‐term microbial and physico‐chemical variability in low‐temperature hydrothermal fluids near 5°S on the Mid‐Atlantic Ridge

Abstract

This study examines the representativeness of low-temperature hydrothermal fluid samples with respect to their chemical and microbiological characteristics. Within this scope, we investigated short-term temporal chemical and microbial variability of the hydrothermal fluids. For this purpose we collected three fluid samples consecutively from the same spot at the Clueless field near 5 degrees S on the southern Mid-Atlantic Ridge over a period of 50 min. During sampling, the temperature was monitored online. We measured fluid chemical parameters, characterized microbial community compositions and used statistical analyses to determine significant differences between the samples. Overall, the three fluid samples are more closely related to each other than to any other tested habitat. Therefore, on a broad scale, the three collected fluid samples can be regarded as habitat representatives. However, small differences are apparent between all samples. One of the Clueless samples even displayed significant differences (P-value < 0.01) to the other two Clueless samples. Our data suggest that the observed variations in fluid chemical and microbial compositions are not reflecting sampling artefacts but are related to short-term fluid variability due to dynamic subseafloor fluid mixing. Recorded temporal changes in fact reflect spatial heterogeneity found in the subsurface as the fluid flows through distinctive pathways. While conservative elements (Cl, Si, Na and K) indicate variable degrees of fluid-seawater mixing, reactive components, including Fe(II), O(2) and H(2)S, show that chemical and microbial reactions within the mixing zone further modify the emanating fluids on short-time scales. Fluids entrain microorganisms, which modify the chemical microenvironment within the subsurface biotopes. This is the first study focusing on short-term microbial variability linked to chemical changes in hydrothermal fluids.

A novel hydrogen oxidizer amidst the sulfur-oxidizing Thiomicrospira lineage

“…16S rRNA genes were PCR amplified using the primers 27 F and 1492 R (Lane, 1991) and the conditions described previously (Perner et al, 2009). Details on the cloning for genes have been described before (Perner et al, 2009).…”

“…16S rRNA genes were PCR amplified using the primers 27 F and 1492 R (Lane, 1991) and the conditions described previously (Perner et al, 2009). Details on the cloning for genes have been described before (Perner et al, 2009). For sequencing of both DNA strands of the 16S rRNA genes from SP-41 and TH-55, the primers 27 F, 1492 R, 562 (5 0 -TAA TCT TGC GAC CGT ACT CC-3 0 ), 719 (5 0 -CTG ACG CTG AGG TGC GAA AG-3 0 ) and 1149 (5 0 -CCC AGT GTG GCT GAT CAT CC-3 0 ) were used.…”

“…All sequences were edited with Lasergene Software SeqMan (DNAStar, Madison, WI, USA). 16S rRNA and hynL gene sequences were edited and analyzed as previously described (Perner et al, 2009;. Phylogenetic trees were calculated using PhyML (Guindon and Gascuel, 2003) and settings as described before (Perner et al, 2009(Perner et al, , 2010.…”

A function-based screen for seeking RubisCO active clones from metagenomes: novel enzymes influencing RubisCO activity

“…Around 200 ml of hydrothermal fluids were concentrated onboard on a 0.2 mm polycarbonate filter and kept at À 20 1C. Detailed sampling procedures and information on the sampling site are described elsewhere (Perner et al, 2007(Perner et al, , 2009(Perner et al, , 2013.…”

Quantification of Microbial Communities in Hydrothermal Vent Habitats of the Southern Mariana Trough and the Mid-Okinawa Trough

“…These studies demonstrated the prevalence of Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, Bacteroidetes, Firmicutes, and various candidate divisions in the hydrothermal system. Due to fluctuations in the environmental conditions, microbial communities in hydrothermally influenced regions exhibit variability on various spatial and temporal scales, including large-scale intra-and inter-field variability (Flores et al 2012;Huber et al 2010;Nunoura and Takai 2009), short-term temporal and spatial variability (Perner et al 2009(Perner et al , 2013, and spatial variability on a small scale of a few centimeters to meters (Nakagawa et al 2005;Takai et al 2004). However, most studies focused on the variability of specific microbial populations in the zone adjacent to hydrothermal vents.…”