The Phylogenetic Tree of Life: A Window into the Ancient History of Hyperthermophiles

In our quest to understand the earliest forms of life on Earth, we often turn to the fascinating world of hyperthermophiles (HT). These microorganisms are capable of surviving in environments that would be hostile to most other living organisms. In fact, some HT strains can even withstand autoclaving at temperatures as high as 121°C. As researchers, we are eager to learn more about today's HT, their environments, properties, and modes of living.

One of the key insights into the ancient history of hyperthermophiles comes from their position within the universal phylogenetic tree of life. This tree provides strong evidence of a hyperthermophilic last common ancestor, which lived around 3.9 billion years ago during the Early Archaean era. At that time, the surface of Earth was much hotter than it is today, with temperatures reaching as high as 80°C or more.

The discovery of HT in hot terrestrial and submarine environments has been a significant find in recent decades. These microorganisms are able to thrive in conditions where most other bacteria would quickly perish. In fact, some HT strains can survive for at least an hour under autoclaving conditions at temperatures above 113°C.

The earliest archaeal phylogenetic lineage is represented by the tiny members of the Nanoarchaeota kingdom, which inhabit submarine hot vents. These microorganisms occupy the short deep branches closest to the root of the phylogenetic tree, suggesting that they are among the oldest forms of life on Earth.

Hyperthermophiles gain energy through inorganic redox reactions involving compounds such as molecular hydrogen, carbon dioxide, sulfur, and ferric and ferrous iron. Members of the genera Pyrodictium and Pyrolobus are particularly noteworthy for their ability to survive extreme temperatures, with some strains able to withstand at least an hour of autoclaving.

Today, hyperthermophilic bacteria and archaea can be found in high-temperature environments around the world, representing the upper temperature border of life. By studying these organisms and their place within the phylogenetic tree of life, we gain a deeper understanding of the ancient history of life on Earth and the conditions that allowed it to thrive.

In conclusion, the study of hyperthermophiles provides a unique window into the early days of life on our planet. These microorganisms have been able to survive and thrive in environments that would be hostile to most other living organisms, and their position within the phylogenetic tree of life offers important insights into the ancient history of life on Earth.

Phylogenetic tree of life