Desulfotomaculum is a genus of Gram-positive, obligately anaerobic soil bacteria. A type of sulfate-reducing bacteria, Desulfotomaculum can cause food spoilage in poorly processed canned foods. Their presence can be identified by the release of hydrogen sulfide gas with its rotten egg smell when the can is first opened. They are endospore-forming bacteria.

A new strain of Desulfotomaculum bacteria has been discovered in a South African gold mine, that exists completely independent of photosynthesis. The bacteria uses the energy provided by radioisotopes to form hydrogen sulfide, H2S, which replaces the hydrogen bonds produced by normal photosynthesis. This discovery holds great promise, as it proves that organisms can obtain energy from sources other than from the sun, which means similar life-forms may be found on other planets in the Solar System.

Desulfotomaculum are straight or curved rods, are highly heat resistant and a free-living fixer of atmospheric nitrogen. They are motile with a peritrichous flagella and are common inhabitants of soil, water, geothermal run-off, insect intestines and in rumen. They also cause "sulphide stinker" spoilage of canned foods.