Regulating the Flood: Deliquescence in Prebiotic Environments

A recent study supported in part by the NASA Astrobiology Program examines the potential role of deliquescent substances in the origin of life. Such substances absorb water vapor from the air, causing the formation of homogeneous, aqueous solutions. In doing so, deliquescent substances could have regulated moisture content for chemical reactions that produced essential molecules for life’s first cells.

In recent years, origin-of-life researchers have recognized the potential importance of wet-dry cycling on the early Earth at the time of life’s origins. In this model, the environment cycles between cool, wet conditions and hot, dry conditions. This wetting and drying could have driven condensation reactions that produced mixtures of biopolymers (such as amino acids combining to form peptide chains). One criticism of the wet-dry model, however, is that it relies on unpredictable events, such as rainstorms and flooding. At a time before enclosed cellular structures existed, these uncontrolled events could have caused over-dilution of the reaction mixtures.

Using glycine as a case study, the recent work found that the addition of deliquescent substances helped to overcome problems associated with over-dilution, and increased the yield of oligomerization reactions by ten-fold. In essence, the study shows that deliquescent substances could have performed the role of modern cells in regulating the volume of prebiotic reaction mixtures. The results provide further support for the importance of wet-dry cycling in driving reactions under prebiotic conditions on the early Earth.

The study, “Prebiotic condensation through wet–dry cycling regulated by deliquescence,” was published in the journal Nature. The work was performed at the NSF/NASA Center for Chemical Evolution (CCE) at the Georgia Institute of Technology in Atlanta, Georgia. The CCE is a collaborative program supported by the National Science Foundation (NSF) and the NASA Astrobiology Program. This research is a critical part of NASA’s work to understand the Universe, advance human exploration, and inspire the next generation. As NASA’s Artemis program moves forward with human exploration of the Moon, the search for life on other worlds remains a top priority for the agency.