Isolation of a novel thermophilic methanogen and the evolutionary history of the class Methanobacteria

The methanogenesis pathway via methanogens date back to the Hadean Earth or the Archaean Earth. These methanogens are considered to have a thermophilic origin and are presently ubiqui-tously distributed across anaerobic environments. The class Methanobacteria comprises meth-anogens that are found extensively in geothermal environments, such as hot springs and hydro-thermal vents, yet their evolutionary history and how they adapted to different temperatures are still unclear. In this study, we isolated a novel species of the class Methanobacteria from a natural hot spring in Tengchong, China. This species can produce methane utilizing hydrogen and carbon dioxide at 65 °C. In addition, we found that members of the class Methanobacteria originated in a geothermal niche and then evolved to adapt to ambient temperatures; during this process, thermal adaptation genes were lost and a wide range of metabolic genes were acquired. This research on methanogen evolution will help us understand how life originated in geothermal environments and then spread extensively across present-day Earth.

(Authors: Zhenbo Lv, Jiaxin Ding, Heng Wang, Jiaxin Wan, Yifan Chen, Lewen Liang, Tiantian Yu, Yinzhao Wang*, Fengping Wang)