(microbiology) A single-celled organism with cell walls but no nucleus or organelles.

(uncommon, possibly nonstandard) plural of bacterium

Any of several bacteria which oxidize inorganic sulfur compounds, especially those bacteria of the genus Thiobacillus

Alternative spelling of sulfur bath

Any of a group of bacteria that oxidize ferrous iron to ferric iron

Mycobacterium lepromatosis, the bacterium that causes leprosy (Hansen's disease).

(informal) The bacterium Deinococcus radiodurans, which is highly resistant to various stresses (especially radiation).

cyanobacterium