Early carbon fixation pathway electrochemistry in simulated hydrothermal-vent interface for the emergence of life theory

• Grant number: 20/13310-1
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: March 31, 2022
• End date: March 30, 2023
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Hamilton Brandão Varela de Albuquerque
• Grantee: Thiago Altair Ferreira
• Supervisor: Reuben Hudson
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: College of the Atlantic (COA), United States
• Associated to the scholarship: 18/12491-2 - Thermodynamic and electrocatalitic aspects in free energy transfer models for the emergency of life on early earth, BP.DR

Abstract

In the investigation of the origin of living systems, the alkaline hydrothermal vents (AHVs) are proposed as one of the most promising scenario to hatchery life on prebiotic Earth. The so-called AHV theory has proposed an energy-transfer mechanism, based on the chemiosmotic theory, as requisite processes of the first steps of emergence of life. Therefore, submarine environments of AHVs on early Earth are estimated to have a specific setting similar to biochemical features in the modern metabolic pathways. It is highlighted the example of the Wood-Ljungdahl (WL) pathway, considered one of the most ancient and universal energy pathways ever discovered. Overall, it is proposed that in an interface between an early AHV and the early ocean, natural electrochemical gradients occurs and are mediated by electronconductive inorganic barriers containing iron-sulfur (Fe-S) mineral minerals, the same that are present in active sites of metalloenzymes in WL pathway. Recent experimental investigations have executed the limiting step of WL, the CO2 reduction to formate by H2, in the AHV conditions. Finally, we describe here a project that seeks to investigate the details of a proposed indirect mechanism of that reduction in the mentioned interface. Thus, it is proposed to study whether there is flow of electrons in the iron-sulfur mineral that couple both redox reaction, the oceanic CO2 reduction and AHV-produced H2 oxidation. Moreover, it is planned to explore the importance of electrochemical potential supporting the natural potential caused by pH and redox gradient estimated in early AHVs. In this context, we expect to relate these parameters also to organic products that are estimated, using, as catalyst, different Fe-S minerals which were already associated to the origin of life theory. (AU)