Chromatiaceae
The Chromatiaceae are the main family of purple sulfur bacteria. Many members conduct an anoxygenic photosynthesis. They are distinguished from the Ectothiorhodospiraceae by producing sulfur globules and storing them inside their cells. Most species of the Ectothiorhodospiraceae are also purple sulfur bacteria, but they store the globules outside their cells. The sulfur is an intermediate in the oxidization of sulfide, which is ultimately converted into sulfate, and may serve as a reserve.
Nitrosococcus belongs to the nitrifying bacteria.
Members are found in both anoxygenic parts of fresh and salt water, and are especially common in stagnant pools, marine habitats, sulfur springs, and soda and salt lakes.
Chromatiaceae bacteria have been the cause for some low-oxygen lakes turning "blood red", such as O.C. Fisher Reservoir in San Angelo, Texas, USA.
