Who first separated bacteria from other protists as a group?

The first person to separate bacteria from other protists as a group was Ernst Haeckel. He was a German biologist, naturalist, philosopher, physician, professor, and artist who discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms, and coined many terms in biology. In his major work "Generelle Morphologie der Organismen" (1866), he proposed a third kingdom of life, the Protista, for "neutral organisms" which were neither animal nor plant, and also a fourth, the Monera, for all organisms without nucleus, mostly bacteria.