Unraveling biogeochemical phosphorus dynamics in hyperarid Mars‐analogue soils using stable oxygen isotopes in phosphate

Abstract

Phosphorus (P) is a crucial bioelement for life on Earth, as it is utilized in the formation of ATP/GTP, genetic materials (DNA/RNA), cell membrane phospholipids, and sugar phosphates formed as intermediate products during sugar metabolism (George et al., 2018). Due to the role P plays in the cycle of life, it is critical to understand P uptake and utilization pathways and their interaction with other key nutrients, such as carbon (C) and nitrogen (N). This is especially true in extreme environments, where organisms are often forced to find novel adaptation strategies for survival and C:N:P ratios may be atypical (Huang et al., 2018; Tian, Chen, Zhang, Melillo, & Hall, 2010). These environments also act as a unique analogue for investigating the potential for life on other planets including Mars, where in the planet's early history active hydrology promoted the release of nutrients making P bioavailable (Komatsu & Ori, 2000;

Phospholipid biomarkers in Mars-analogous soils of the Atacama Desert

“…The microbial concentrations converted from PLFAs were on the same level as the viable cell counts determined by trypan blue assay (Table S2) of low precision, and were consistent with the cell numbers determined by other studies (Connon et al ., 2007; Lester et al ., 2007; Shirey, 2013). By analysing the relationships between PLFAs and TOC as well as microbial P (Shen et al ., 2019, 2020 b ), we can understand the origin and degradation of organics in the extremely dry soils. Within the hyperarid core, all the concentrations of PLFAs, TOC and microbial P shared an identical trend: PONR site had the highest biomass, MES had the lowest (Azua-Bustos et al ., 2015) and Yungay was in-between (Maier et al ., 2004; Kuhlman et al ., 2008; Azua-Bustos et al ., 2012).…”

“…4a and Table 3), indicating PLFAs degraded slower at increasing aridity (Ewing et al ., 2007; Wilhelm et al ., 2017; Jones et al ., 2018). Although the degradation of PLFAs was dependent on ambient temperatures (Ranneklev and Baath, 2003), the mean annual temperatures within all Atacama sampling sites were 17.8 ± 1.3°C (Table 1) (Shen et al ., 2020 b ). Thus, the impacts of variable temperatures should be insignificant, and the aridity was the primary regulator of PLFA degradation.…”

“…Concentrations of microbial P extracted using the sequential soil phosphate extraction method (Tamburini et al ., 2018) were reported in Shen et al . (2020b). Viable cells were determined using trypan blue assay, and the viability hereafter is defined as the percentage of viable cells.…”

Geochemical proxies for water-soil interactions in the hyperarid Atacama Desert, Chile

“…Under these conditions, the soil CO2 concentrations are too low for the formation of significant amounts of carbonates, which are commonly present in arid soils (Ewing et al, 2006). Hence, the Atacama Desert is of interest for studying the dry limits of life and has been used as an analog site for assessing the habitability on Mars (e.g., Warren-Rhodes et al, 2006;Azua-Bustos et al, 2018;Schulze-Makuch et al, 2018;Huang et al, 2020;Shen et al, 2020;Schulze-Makuch et al, 2021).…”

A review of phosphate oxygen isotope values in global bedrocks: Characterising a critical endmember to the soil phosphorus system

“…–25‰), and 5'‐nucleotidase hydrolysis (–10‰) all cause a negative shift in isotope values ( Liang and Blake , 2006), whilst inorganic pyrophosphatase will cause a positive shift based on equilibrium at most modern temperature and combinations. Therefore, highly positive isotope values (+20 to +25‰), which have been significantly shifted away from an igneous bedrock endmember can only reasonably be attributed to the microbial cycling of P via inorganic pyrophosphatase ( Shen et al, 2020).…”