Spontaneous Formation of Prebiotic Compartment Colonies on Hadean Earth and Pre‐Noachian Mars**

Abstract

Prominent among the models for protocells is the spherical biosurfactant shell, freely suspended in aqueous media. This model explains initial, but not subsequent events in the development process towards structured protocells. Taking into consideration the involvement of naturally occurring surfaces, which were abundant on the early Earth, feasible and productive pathways for the development of primitive cells are reported. Surfaces intrinsically possess energy, easily utilized by the interfacing amphiphiles, such as lipids, to attain selforganization and spontaneous transformations. This work shows that the physical interaction of phospholipid pools with 20 Hadean Earth analogue materials as well as a Martian meteorite composed of fused regolith representing the ancient crust of Mars consistently lead to the shape transformation and autonomous formation of surfactant compartment assemblies. Dense, colony-like protocell populations grow from these lipid deposits, predominantly at the grain boundaries or cleavages of the investigated natural surfaces, and remain there for several days. The model protocells in this study are able to autonomously develop, transform and pseudo-divide, and encapsulate RNA as well as DNA. Moreover, they can accommodate nonenzymatic, DNA strand displacement reactions. These findings suggest a feasible route towards the transformation from nonliving to living entities, and provide fresh support for the 'Lipid World' hypothesis.

Colony-like Protocell Superstructures

“…This transformation is presumably lipid dependent, as vesicles made from certain lipid species did not exhibit this behavior . Most recently, we showed the formation of colony-like model protocells emerging from the molecular lipid films on early Earth minerals and a Martian meteorite …”

“…14 Most recently, we showed the formation of colony-like model protocells emerging from the molecular lipid films on early Earth minerals and a Martian meteorite. 15 Here we report the stepwise formation and growth of protocell superstructures containing tens to thousands of membranous compartments, originating from a single onionshell lipid reservoir. Inside a lipid compartment, several layers of smaller vesicles grow from the surface up, leading to a densely packed pool of compartments of similar shape and size, reminiscent of bacterial colonies.…”

“… 14 Most recently, we showed the formation of colony-like model protocells emerging from the molecular lipid films on early Earth minerals and a Martian meteorite. 15 …”

Protocells: Milestones and Recent Advances

“…[187,188] Köksal et al utilized high-energy surfaces to transform spreading double lipid bilayers into giant membranous compartments interconnected by lipid nanotubes. [189,190] In this autonomously occurring process, common lipid agglomerates are consistently driven to non-trivial lipid structures by surface free energy minimization. Similar to bulk assembly, very few fundamental assumptions are required for this process in a prebiotic setting, essentially the availability of water, biosurfactants and suitable environmental parameters.…”