The Collaborative International Dictionary
Microbion
Microbe \Mi"crobe\, Microbion \Mi*cro"bi*on\, n. [NL. microbion, fr. Gr. ? little + ? life.] (Biol.) A microscopic organism; a microorganism; -- particularly applied to bacteria and especially to pathogenic forms; as, the microbe of fowl cholera.
Wiktionary
microbion
n. (context archaic English) A microbe.