Living at the Extremes: Extremophiles and the Limits of Life in a Planetary Context

Abstract

Prokaryotic life has dominated most of the evolutionary history of our planet, evolving to occupy virtually all available environmental niches. Extremophiles, especially those thriving under multiple extremes, represent a key area of research for multiple disciplines, spanning from the study of adaptations to harsh conditions, to the biogeochemical cycling of elements. Extremophile research also has implications for origin of life studies and the search for life on other planetary and celestial bodies. In this article, we will review the current state of knowledge for the biospace in which life operates on Earth and will discuss it in a planetary context, highlighting knowledge gaps and areas of opportunity.

The Interior and Atmosphere of the Habitable-zone Exoplanet K2-18b

“…Living organisms are known to thrive in Earth's extreme environments (extremophiles). Their living conditions span the phase space of liquid H 2 O up to ∼1000 bar pressures at the bottom of the Marianas Trench and ∼400 K temperatures near hydrothermal vents (e.g., Merino et al 2019).…”

Exo-Ocean Exploration with Deep-Sea Sensor and Platform Technologies

“…Prokaryotic-like life (i.e., unicellular) could be (theoretically) inhabiting exo-oceans (Merino et al, 2019). Traces of biological activity could then be detectable from tens of meters up to kilometers as has been accomplished on Earth's oceans with available deep-sea sensor technologies .…”

Overview and perspectives of Astrobiology

“…对这些极端环境中 微生物的研究改变了人们对生命生存极限的认识. 目 前已在40~70 km高度的临近空间、一万米以下的深 海、120°C的高温环境、零下17°C的低温环境、常年 干燥的沙漠、南极永久冻土带等极端环境中都发现了 微生物的存在 [13] , 这拓宽了宜居环境的定义和范畴 [71] . 这些极端环境可以类比太阳系内一些天体, 如临近空 间、沙漠、南极永冻土带可以类比现在的火星环境, 深海和冰下湖可以类比土卫二和木卫二内部的海洋环 境等.…”