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How did bacteria form?
It is known that earth’s earliest organisms were thermophilic, or able to dwell in hot environments. These organisms engaged in chemotropic metabolism — they converted inorganic substances, such as sulfur and carbon, into energy to live. This process is similar to how we use food, water, and oxygen to generate energy.

The predecessors of modern bacteria differ in much more than age. The Archean era, which records the first billion years of Earth’s geologic history, ended 2.5 billion years ago. It was at this point that the earth’s biosphere must have changed and the atmospheric temperature reached 72 degrees Celsius. This is the maximum temperature at which photosynthesis can take place.Near the end of this era, about 2.7 to 2.9 billion years ago, according to Blank, stromatolites, organisms of the group Bacteria that use photosynthesis to create energy without producing oxygen, first appeared.


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