Preservation of ATP in Hypersaline Environments

Abstract

High concentrations of particulate ATP were found in the anoxic brines of the Orca Basin and East Flower Garden, Gulf of Mexico. Other measurements indicative of growth and respiration suggested that the microbial community in the brines was inactive, but somehow the ATP associated with the cells persisted. Conceivably, when cells growing just above the interface sank into the brine, the increased osmotic stress could elicit an osmoregulatory response resulting in increased ATP. It was also possible that hydrolytic enzymes were inactivated, resulting in the preservation of ATP. Experiments in which a culture of marine bacteria was suspended in menstrua of different salinities comparable to those found across the Orca Basin interface revealed that as salinity increased, ATP increased threeto sixfold. Within 24 h the ATP fell to its initial level and remained at that concentration for 3 days, at which time the experiment was terminated. In contrast, the control suspensions, at a salinity of 28%o (grams per liter) had 1/10th of the initial ATP concentration when the experiment was ended. Cells were also exposed to killing UV irradiation, enabling us to demonstrate with absolute certainty that cellular ATP could be preserved. At the end of the experiment, the viable component of the population was reduced by orders of magnitude by UV irradiation, but the ATP levels of the cells suspended in brine did not decrease. In certain environments it appears that the conventional analytical tools of the microbial ecologist must be interpreted with caution.

Current state of athalassohaline deep‐sea hypersaline anoxic basin research—recommendations for future work and relevance to astrobiology

“…Preservation may be attributed to the complete inhibition of DNases/RNases by abundant Cl − ions and DNA stabilization by Mg 2+ cations as they are strongly attracted to the phosphate backbone of DNA (Luck and Zimmer, 1972; Chatake and Sunami, 2013; Serec et al ., 2016). The ability of MgCl 2 to preserve other relevant biomarkers such as lipids and ATP has been previously noted, but to‐date has been poorly described (Tuovila et al ., 1987; Turich and Freeman, 2011). Studying the preservation of biomarkers and microbial activities in the Kryos, Discovery and Hephaestus basins would be a beneficial and strategically relevant pursuit for future planetary science missions.…”

Microbiology of the Red Sea (and other) deep‐sea anoxic brine lakes

“…Evidence of the presence of active microbial communities in Orca Basin was obtained shortly after its discovery (LaRock et al ., 1979). A clear decrease in microbial activity when moving from the interface to the deeper brine was later reported and coincided with a shift from predominantly autotrophic to heterotrophic metabolism (LaRock et al ., 1979; Tuovila et al ., 1987). Additional studies showed that the majority of microbes present at the interface were manganese‐oxidizers (Van Cappellen et al ., 1998).…”

Stable Brine Layers beneath Europa’s Chaos

“…Ion fractionation processes (not explored here) may preferentially enrich the remaining melt in kosmotropic ions (those that are stabilizing to life) such as Mg 2+ or in chaotropic ions (destabilizing to life) such as Cl − (Hallsworth et al 2007) depending on the fractionation pathways that occur during solidification. While high-salinity, low-water-activity solutions and precipitated salts may be challenging for life, they may also help to preserve records of life (Tuovila et al 1987;Borin et al 2008) within the ice shell. Measurements of the ionic composition of shallow water reservoirs by future remotesensing missions may depend on whether such reservoirs are plume sources (Walker & Schmidt 2018;Chivers et al 2021).…”