halobacterium vs halobacter

halobacterium and halobacter both are nouns.

Word	Noun	Adjective	Verb	Adverb
halobacterium	Yes	No	No	No
halobacter	Yes	No	No	No

As nouns, halobacterium and halobacter are synonyms defined as:

halobacterium and halobacter: halophiles in saline environments such as the Dead Sea or salt flats

Other synonyms of halobacterium include halobacteria.

halobacterium (noun)	halobacter (noun)
halophiles in saline environments such as the Dead Sea or salt flats	halophiles in saline environments such as the Dead Sea or salt flats