With all the major evolution done so early, microbe evolution has been retired for a very long time. No wonder we can’t evolve new pathways in the lab!
From ScienceDaily
New research shows that for microbes, large-scale evolution was completed 2.5 billion years ago.
“For microbes, it appears that almost all of their major evolution took place before we have any record of them, way back in the dark mists of prehistory,” said Roger Buick, a University of Washington paleontologist and astrobiologist.
All living organisms need nitrogen, a basic component of amino acids and proteins. But for atmospheric nitrogen to be usable, it must be “fixed,” or converted to a biologically useful form. Some microbes turn atmospheric nitrogen into ammonia, a form in which the nitrogen can be easily absorbed by other organisms.
About 2.5 billion years ago some microbes evolved that could add oxygen to ammonia to produce nitrate. These microbes are on the last, or terminal, branches of the bacteria and archaea domains of the so-called tree of life, and they are the only microbes capable of carrying out the step of adding oxygen to ammonia. This indicates that large-scale evolution of bacteria and archaea was complete about 2.5 billion years ago, Buick said. “Countless bacteria and archaea species have evolved since then, but the major branches have held,”
“All microbes are amazing chemists compared to us.” Buick said.