The Great Oxygenation would have wiped out most of the world's obligate anaerobic bacteria.

Butyrate is produced as end-product of a fermentation process solely performed by obligate anaerobic bacteria.

Clostridium septicum is a gram positive, spore forming, obligate anaerobic bacterium.

Clostridium novyi (oedematiens) a Gram-positive, endospore- forming, obligate anaerobic bacteria of the class clostridia.

The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, rod-shaped, obligate anaerobic bacterium Clostridium tetani.