Organisms Evolutionarily Closest to the Origin of Life

Abstract

It was reported in 1983 that bacteria were present around the hydrothermal vent at 2650 m in depth where the temperature was 350°C (Baross and Deming, 1983), Although it seemed curious that organisms could reside at 350°C, it was recognized at that time that the organisms could reside at a high temperature of 350°C, because the pressure is high at 2650 m depth (265 atm) and water remains in liquid form. Baross and Deming (1983) reported that they had succeeded in culturing the bacteria in their laboratory at 250°C and under 250 atm. The bacteria grew at the generation time of 40 min and methanogens were included among them. Namely, it was found that some of the methanogens could grow at 250°C and at 250 atm. From these findings it seemed that some of the methanogens might have resided even at the geological age when the temperature of the surface of Earth was still more than 100°C, even though their growing temperature, 250°C, was not exactly verified.