Biomarker Profiling of Microbial Mats in the Geothermal Band of Cerro Caliente, Deception Island (Antarctica): Life at the Edge of Heat and Cold

Abstract

Substrate-atmosphere interfaces in Antarctic geothermal environments are hot-cold regions that constitute thin habitable niches for microorganisms with possible counterparts in ancient Mars. Cerro Caliente hill in Deception Island (active volcano in the South Shetland Islands) is affected by ascending hydrothermal fluids that form a band of warm substrates buffered by low air temperatures. We investigated the influence of temperature on the community structure and metabolism of three microbial mats collected along the geothermal band of Cerro Caliente registering 88°C, 8°C, and 2°C at the time of collection. High-throughput sequencing of small subunit ribosomal ribonucleic acid (SSU rRNA) genes and Life Detector Chip (LDChip) microarray immunoassays revealed different bacterial, archaeal, and eukaryotic composition in the three mats. The mat at 88°C showed the less diverse microbial community and a higher proportion of thermophiles (e.g., Thermales). In contrast, microbial communities in the mats at 2°C and 8°C showed relatively higher diversity and higher proportion of psychrophiles (e.g., Flavobacteriales). Despite this overall association, similar microbial structures at the phylum level (particularly the presence of Cyanobacteria) and certain hot-and cold-tolerant microorganisms were identified in the three mats. Daily thermal oscillations recorded in the substrate over the year (4.5-76°C) may explain the coexistence of microbial fingerprints with different thermal tolerances. Stable isotope composition also revealed metabolic differences among the microbial mats. Carbon isotopic ratios suggested the Calvin-Benson-Bassham cycle as the major pathway for carbon dioxide fixation in the mats at 2°C and 8°C, and the reductive tricarboxylic acid cycle and/or the 3-hydroxypropionate bicycle for the mat at 88°C, indicating different metabolisms as a function of the prevailing temperature of each mat. The comprehensive biomarker profile on the three microbial mats from Cerro Caliente contributes to unravel the diversity, composition, and metabolism in geothermal polar sites and highlights the relevance of geothermal-cold environments to create habitable niches with interest in other planetary environments.

Fingerprinting molecular and isotopic biosignatures on different hydrothermal scenarios of Iceland, an acidic and sulfur-rich Mars analog

“…2 f). This apparent anomaly was hypothesized to be related to the characteristic episodic nature of thermal activity in hydrothermal systems such as fumaroles (see text S8 ), where the continuous variability of temperature with time 38 , 39 allows the alternation in time of microbial communities with different tolerance to temperature 40 . The temporal variation of microbial populations with temperature imprints the substrate with biosignatures of both present and past communities 39 , 41 .…”

“…This apparent anomaly was hypothesized to be related to the characteristic episodic nature of thermal activity in hydrothermal systems such as fumaroles (see text S8), where the continuous variability of temperature with time 38,39 www.nature.com/scientificreports/ with different tolerance to temperature 40 . The temporal variation of microbial populations with temperature imprints the substrate with biosignatures of both present and past communities 39,41 . Thus, the highest detection of thermophile biomarkers in IF-20 was considered to be likely recording a larger presence of thermophiles in the past, when a much higher temperature than that measured during the study sampling surely took place.…”

The Complex Molecules Detector (CMOLD): A Fluidic-Based Instrument Suite to Search for (Bio)chemical Complexity on Mars and Icy Moons

“…We have been using FSI for many years, both in the laboratory and in multiple field campaigns, and the sensitivities of detection obtained range from 0.1 to 10 ppm for biochemical compounds and 10 3 to 10 4 cells or spores per milliliter (Fernandez-Calvo et al , 2006 ; Rivas et al , 2008 ; Parro et al , 2011a ; Blanco et al , 2013 ; Lezcano et al , 2019 ; García-Descalzo et al , 2019 ; Sánchez-García et al , 2020 ).…”

Fast Degradation of Hydrogen Peroxide by Immobilized Catalase to Enable the Use of Biosensors in Extraterrestrial Bodies

“…To address this limitation, a number of liquid-based analytical techniques have been proposed (Blanco et al, 2017;Ribette et al, 2019). Out of those, immunoassays, electrochemical sensors (Thomson et al, 2020), and microfluidic capillary electrophoresis technologies hold the most promise in terms of power requirement, weight, sensitivity, and ability to detect biomarkers in model systems (Derveni et al, 2012;Sims et al, 2012;Willis et al, 2012;Butterworth et al, 2015;Mathies et al, 2017Mathies et al, , 2019Moreno-Paz et al, 2018;García-Descalzo et al, 2019;Lezcano et al, 2019). Unfortunately, even low concentrations of H 2 O 2 present in the sample could interfere with all of these platforms because it may induce structural changes in the antibodies (required for selectivity in immunoassays) or through oxidizing the dyes used in fluorescence-based systems (Stockton et al, 2013).…”