Periodic Reporting for period 2 - COEVOLVE (Coevolution of Life and Planet: role of trace metal availability in the evolution of biogeochemically relevant redox metalloenzymes)
Période du rapport: 2022-11-01 au 2024-04-30
Earth and Life have coevolved over time, influencing each other’s evolutionary trajectory and ultimately keeping our planet habitable for the last 4 billion years. Microorganisms in the environment play a large role in mediating the interactions between Earth’s geosphere and biosphere, controlling a large portion of the cycle of elements and nutrients. The majority of the key microbial chemical reactions that control the cycle of elements are carried out by a small set of proteins containing a redox-sensitive transition metal as their core catalytic center. Elements used include, among others, transition metals such as Fe, Mo, W, Zn, Cu, V, Mn, Ni and Co and non-metals like S and Mg. The availability of these metals is largely controlled by abiotic reactions in diverse ecosystems, and it has changed over the course of Earth’s history as a result of changing redox conditions, particularly global oxygenation. Empirical data from diverse fields suggest that the availability of transition metals can influence the type of microbial communities, and in turn their ecosystem functions, found in different ecosystems. Despite this, there is a lack of fundamental knowledge on distribution and availability of transition metals in controlling microbial diversity. COEVOLVE will elucidate the impact of transition metal availability on microbial functional diversity, combining fieldwork, laboratory experiments, and computational approaches. COEVOLVE will: 1) investigate the relationship between the availability of trace metals and microbial functional diversity in extant ecosystems and organisms; 2) link metabolic diversity and metal availability to different geological, geochemical, and mineralogical conditions; 3) link metabolic diversity and dependence on metal availability to the emergence and evolution of different metabolisms; and 4) determine the timing of major steps in metabolic evolution and link them to geochemical proxies of planetary surface redox change. Understanding the role of trace metal environmental distribution and availability in influencing microbial functional diversity might hold the key to understanding the co-evolution of Life and Planet Earth, unlocking a number of important discoveries at the core of diverse fields such as earth sciences, astrobiology, microbial ecology, and biotechnology.
In the first reporting period we have set up and validated the instruments and laboratory protocols necessary for the determination of trace elements in diverse environmental matrices. We have developed and validated a large-scale sampling approach necessary to investigate coupled geosphere-biosphere processes. We have developed and are validating a new metagenomic annotation pipeline with an emphasis on biogeochemistry and metalloprotein diversity to facilitate the correlations with the geochemical data. We have also started the sampling and analysis of diverse geothermal ecosystems used as a model to understand the effect of trace element availability in controlling microbial diversity. We have added to the newly produced data a set of ~200 publicly available metagenomes, reannotated following our new pipeline, and added a number of new metagenomic samples from diverse tectonic settings. Additionally, we are exploring the effect of the differential availability of transition metals on the physiology of model microbial cultures, assessing their role in controlling metabolic shifts among alternative electron acceptors.
We are in the process of developing and validating specific statistical approaches to identify large scale relationships between the distribution and availability of trace elements with microbial diversity and functions. While the produced data are currently being processed, preliminary results suggest a strong role of trace elements in controlling microbial diversity at a global scale. Additionally, we have started to lay the foundation necessary for the large scale sampling effort foreseen in the project, and validated all the laboratory and field methods. Preliminary results from laboratory cultures suggest the presence of a strong physiological response in model organisms to variable levels of trace elements. These results are especially encouraging and might lead to a breakthrough in our understanding of the relationship between trace element availability and microbial functional diversity.