anaerobes

Within the gut there is going to be obligate anaerobes (killed by atmospheric O2) and facultative anaerobes (can survive in both oxygen rich and oxygen deplete environments).

Some bacteria of the genus Clostridium (putrescent anaerobes) are able to ferment amino acids as well as carbohydrates.

Then cyanobacteria gave us photosynthesis and free oxygen, rendering anaerobes' dominance an edge-case at the dawn of life.

Sure the faculatative anaerobes will survive, but this is going to create an imbalance in the populations being transplanted.

Most of the organisms in the gut are strict anaerobes which are killed on contact with oxygen.

The former are caused by obligate aerobes, the latter by facultative anaerobes and are far more dangerous.

It's to remove the biofilm that exists at and below the gumline containing facultative anaerobes which cause periodontal disease.

Therefore, it has been known since soon after they were first discovered that they are obligate anaerobes.

You can have gorgeous, cavity-free teeth that fall out because the supporting structures have been resorbed and destroyed by these anaerobes.

So there are still pockets environments that can support such anaerobes, but they are rare.

Like every other organism except for anaerobes (mostly microbes, some fungi) they need oxygen in order to burn fuel for cellular processes.

Frequent efficient removal of this biofilm is important for growth of commensal species, and reduction in pathogenic anaerobes that can cause disease.

Humans are a sophisticated biological weapon designed by the anaerobes to trigger the "clathrate gun" and return Earth to a non-oxygen-rich regime.

- the web’s network advantage had evaporated If anything this argues against the thesis that "make anaerobes do photosynthesis" is insufficient.

All life processes produce waste that is dangerous to that which created it, yet we do not call photosynthesis "non renewable" despite oxygen being toxic to obligate anaerobes.

Anaerobes instead use less-oxidizing substances such as nitrate (NO3), fumarate (C4H2O24), sulfate (SO24), or elemental sulfur (S).

Anaerobes probably thought the first air-breathers were an anomaly, too.