Originally Posted by Voidrider
There are some pretty strange anaerobic bacteria that can grow and multiply in some pretty bizarre environments. Anaerobic bacteria tend to give off methane as a waste product. (Aerobic bacteria tend to give off carbon dioxide. Facultative bacteria can live in either aerobic or anaerobic conditions and can give off either gas - tricky!)
I always figured that heat and fluid/mechanical action killed off bacteria, but a few always survived, and they would just feast on the dead ones and the population would explode again. Even the original oil isn't added to the forks in a "clean room". Always going to be a few little critters getting into the system somewhere.
Not that I think they're involved with "Original Jap Fork Oil Horrible Stench", but one real nasty anaerobe, a sulfate-reducing bacteria (SRB, formally known as Desulfovibrio desulfuricans), makes H2S (hydrogen sulfide). Methane gas in farts may ignite, but the strong "aroma" is H2S.
Take a look:
The corrosion of sewers and the control of odor are the major operational and maintenance problems in wastewater collection systems. The generation of hydrogen sulfide and subsequent sulfuric acid results from microbially mediated reactions, by sulfate‐reducing bacteria (SBR) and sulfide‐oxidizing bacteria. This review covers pertinent information about sulfate reduction‐induced problems in general and SBR in particular. Metabolism with respect to carbon, energy, and sulfur sources, ecology, growth factors (dissolved oxygen, temperature, pH, and sulfide), and the competitive effects of methane‐producing bacteria on SBR are discussed. Because metals react with sulfide to form metal sulfide precipitates with extremely low solubilities, metal interactions in sulfate reduction environments are discussed.