Bacteroidetes

Bacteroidetes or Bacteroidota are a large phylum of gram-negative bacteria with a wide distribution in the environment, including soil, sediments, lakes, seawater, and the digestive tract. of the animals.

The group includes six classes. The class Bacteroidia is by far the most studied and includes the genus Bacteroides, an organism abundant in the feces of warm-blooded animals including humans, and Porphyromonas, a group of organisms that inhabit the human oral cavity. Members of the genus Bacteroides are opportunistic pathogens. The other classes of Bacteroidetes are rarely pathogenic to humans. Representative species of the orders Flavobacteriales, Sphingobacteriales and Cytophagales are Flavobacterium mizutaii, Sphingobacterium antarcticum and Cytophaga columnaris respectively.

Researcher Jeffrey Gordon et al. found that obese humans and mice have gut flora with a lower percentage of Bacteroidetes bacteria and a higher percentage of Firmicutes. However, it is unknown if Bacteroidetes prevents obesity or that this intestinal flora is simply selected by the intestinal conditions of the non-obese.

Phylogeny

Several proteins are common to both Flavobacteriales and Bacteroidales, indicating that these orders share a common ancestor excluding other Bacteroidetes. The common ancestor of Bacteroidetes appears to have been a thermophile given the basal position of the four thermophilic groups. Chlorobia, formerly considered an independent phylum, acquired photosynthesis from a shared ancestor with traditional (non-thermophilic) Bacteroidetes.

A somewhat agreed phylogeny in the GTDB database and the Annotree is the following: