The bacterium Clostridium botulinum, causing botulism (a form of food poisoning) is an obligate anaerobic, endospore forming, Gram positive, rod-shaped bacterium found in soil and in many fresh water sediments.
This bacterium produces a toxin, called botulinum toxin, which is the most toxic substance known (causes fatal food poisoning) but in minute doses, it is used to treat certain conditions involving muscle dysfunction.