Microbes of the Rocks and Permafrost, an Extraterrestrial Analog

Abstract

The polar region is characterized by low temperatures, dry air, strong UV, and poor nutrient. Even though Earth has sufficient oxygen, the polar region is a good analog of the extraterrestrial environment such as Mars. Permafrost is a frozen ground with a temperature below 0°C for two or more years, which lies on approximately 25% of Earth’s terrestrial surface. Despite the long subzero temperature and poor water availability, a diverse group of microbes is living in permafrost. Permafrost is a good source of extremophiles. Methanogenic archaea from Siberian permafrost, for example, can survive in the Martian subsurface, showing a remarkable dry condition, osmotic stress, low temperatures, and radiation. Rock is also a sheltered habitat to avoid environmental stresses in the polar region. In fact, microbes of rocks are a major focus of many investigations of life in harsh environments or studies with astrobiological implications. In this lecture, I would like to introduce the diversity and function of microbes living in Arctic rocks and permafrost. From these extreme microbes, I would also like to find the insights of extraterrestrial life that may be living outside the Earth.