Biogeochemical probing of microbial communities in a basalt‐hosted hot spring at Kverkfjöll volcano, Iceland

Abstract

We investigated bacterial and archaeal communities along an ice-fed surficial hot spring at Kverkfjöll volcano-a partially ice-covered basaltic volcano at Vatnajökull glacier, Iceland, using biomolecular (16S rRNA, apsA, mcrA, amoA, nifH genes) and stable isotope techniques. The hot spring environment is characterized by high temperatures and low dissolved oxygen concentrations at the source (68°C and <1 mg/L (±0.1%)) changing to lower temperatures and higher dissolved oxygen downstream (34.7°C and 5.9 mg/L), with sulfate the dominant anion (225 mg/L at the source). Sediments are comprised of detrital basalt, low-temperature alteration phases and pyrite, with <0.4 wt. % total organic carbon (TOC). 16S rRNA gene profiles reveal that organisms affiliated with Hydrogenobaculum (54%-87% bacterial population) and Thermoproteales (35%-63% archaeal population) dominate the micro-oxic hot spring source, while sulfur-oxidizing archaea (Sulfolobales, 57%-82%), and putative sulfur-oxidizing and heterotrophic bacterial groups dominate oxic downstream environments. The δ C (‰ V-PDB) values for sediment TOC and microbial biomass range from -9.4‰ at the spring's source decreasing to -12.6‰ downstream. A reverse effect isotope fractionation of ~3‰ between sediment sulfide (δ S ~0‰) and dissolved water sulfate (δ S +3.2‰), and δ O values of ~ -5.3‰ suggest pyrite forms abiogenically from volcanic sulfide, followed by abiogenic and microbial oxidation. These environments represent an unexplored surficial geothermal environment analogous to transient volcanogenic habitats during putative "snowball Earth" scenarios and volcano-ice geothermal environments on Mars.

Volcanic controls on the microbial habitability of Mars‐analogue hydrothermal environments

“…The mineralogy from Arsia Mons has not been studied as a thick mantle of dust inhibits mineralogical spectroscopic measurements (Scanlon et al., 2014). Microbial communities previously investigated in these active Icelandic volcano–ice systems are dominated by microorganisms employing metabolisms such as anaerobic and microaerobic chemolithotrophic Fe reduction, sulphate reduction and sulphide oxidation (Cousins et al., 2018; Gaidos et al., 2009; Marteinsson et al., 2013).…”

“…Likewise, within either ‘warm’ or ‘cold’ climatic scenarios on Mars (Wordsworth, 2016), surface volcano–ice interaction is a relevant mechanism for habitability (Cousins & Crawford, 2011; Cousins et al., 2018). Glaciovolcanism on Mars may have occurred throughout Mars's history, with the emplacement of lava flows and magma bodies into the planet's cryosphere (Chapman et al, 2000; Cousins & Crawford, 2011; Head and Wilson, 2007).…”

Sample Collection and Return from Mars: Optimising Sample Collection Based on the Microbial Ecology of Terrestrial Volcanic Environments

“…These spatial variations in microbial diversity are observed in all volcanic environments investigated (Table 1) ranging from geothermal fumaroles (Soo et al 2009;Benson et al 2011;Wall et al 2015) to weathered exposed crystalline and glassy volcanic rocks Kelly et al 2010, ash and soils (Gomez-Alvarez et al 2006;Ibekwe et al 2007), and mud volcanoes (Huang et al 2016;Dahigaonkar and Chavan 2018). Variations in the microbial ecology caused by temperature and geochemical spatial gradients were examined in detail in a geothermal setting in Iceland, where differences in microbial phylogeny, function and their associated isotope fractionation values were found in single geothermal outflows (Cousins et al 2018). shows that each rock hosts a distinct community.…”

Boric Acid (H3(BO3): Recognize The Molecular Interactions in Solutions

“…(35) Keberadaannya di alam sangat berlimpah, beberapa dari senyawa ini ditemukan dalam keadaan bebas pada beberapa distrik vulkanik. (36)(37)(38) Senyawa yang sering dikenal dengan boraks ini, merupakan monobasa dari asam lewis lemah yang memiliki bentuk segitiga datar. Senyawa ini mampu larut di dalam alkohol, cukup larut di dalam piridina dan sangat sedikit larut jika dilarutkan di dalam aseton.…”