Sulfoquinovose (SQ), it’s quite a mouthful :)
SQ is a abundant sugar produced by photosynthetic organisms, such as leafy green vegetables, as a source of carbon and sulfur. It is the only sugar that contains sulfur, required to build proteins that sustain bacteria.
Researchers have now found out that good gut bacteria, such as E. coli produce an enzyme, YihQ, that absorbs and metabolises SQ, thereby releasing sulfur into the immediate environment where it is then recycled and used by other microorganisms.
The short version of the pathway goes something like this:
Interestingly, one study has previously shown that thiosulfate was reduced in patients with bacterial overgrowth (for example when pathogenic bacteria multiply vigorously at the expense of the good gut bacteria) and who were receiving antibiotics (oxytetracycline or metronidazole). The researchers concluded that the resident bacterial flora contributes to thiosulfate in the human body.
Primary sources:
http://phys.org/news/2016-02-sweet-discovery-leafy-greens-key.html
http://www.nature.com/nchembio/journal/vaop/ncurrent/full/nchembio.2023.html