The identification of sulfide oxidation as potential metabolism driving primary production on late Noachian Mars

• Main Authors: Macey, Michael C, Fox-Powell, Mark, Ramkissoon, Nisha K, Baharier, Bea, Oliver, James A W, Stephens, Ben, Schwenzer, Susanne P, Pearson, Victoria K, Cousins, Claire R, Olsson-Francis, Karen
• Format: Conference Object
• Language: unknown
• Published: 2020
• Subjects: Arctic; Colour Peak; Rian; Yellowknife; Yellowknife Bay
• Online Access: https://oro.open.ac.uk/78293/; https://oro.open.ac.uk/78293/1/LPSC%202021%20Macey%20SUBMIT.pdf; https://www.hou.usra.edu/meetings/lpsc2021/pdf/1139.pdf

Introduction: The surface of Mars cannot sus-tain liquid water today, but there is evidence for the extended presence of liquid water during the Noa-chian era [1-2]. The transition of the martian cli-mate from the wet Noachian to the dry, late Hespe-rian would have resulted in saline and sulfur-rich surface waters [1-4]. Terrestrial analogue environ-ments that possess a similar chemistry to these pro-posed waters can be used to develop an understand-ing of the diversity of organisms that could have persisted under such conditions. Combining this with laboratory simulation experiments, which ena-ble a greater level of accuracy regarding the chemi-cal environment, allows for concepts regarding di-versity and function to be developed. Here we present the chemistry and microbial community of the highly reducing sediment of the springs of Colour Peak, a sulfidic and saline spring system located within the Canadian High Arctic [2]. We also present details of the viability of this mi-crobial community when grown in defined, simulat-ed martian fluid chemistries based on the chemistry of Rocknest at Gale crater in combination with ba-saltic and iron enriched martian simulants. Methodology: In this study, the elemental com-position of the fluids and sediment porewater of Colour Peak was determined by ICP-OES. This data was compared with a range of fluid chemistries, including those from other analogue environments and martian brines, the composition of which were determined based on the chemistry of the “Rock-nest” sand sample at Yellowknife Bay, Gale crater (Mars) by thermochemical modelling [5]. The fluid chemistry derived from the thermochemical model-ling was used to calculate Gibbs energy values to identify metabolic pathways that could be energeti-cally feasible. Molecular techniques were also used to investigate the microbial community of the sedi-ment of the Colour Peak Springs. Both DNA and RNA were extracted from the microbes in the sedi-ment using a novel extraction technique that was developed to overcome ...