Chlorobium

Chlorobium is a genus of obligate anaerobic bacteria belonging to the phylum Chlorobiota. These microorganisms are notable for their ability to perform anoxygenic photosynthesis, meaning they can produce energy from light without releasing oxygen as a byproduct. They are often referred to as green sulfur bacteria.

The photosynthetic apparatus of Chlorobium is located in specialized structures called chlorosomes, which are attached to the inner surface of the cytoplasmic membrane. These chlorosomes contain bacteriochlorophylls and carotenoids, pigments that absorb light energy. Unlike plants, Chlorobium uses reduced sulfur compounds, such as hydrogen sulfide, as electron donors for photosynthesis, releasing elemental sulfur or sulfate.

Chlorobium species are found in diverse environments where light is available and oxygen is absent, including anoxic sediments, stratified lakes, and hot springs. Their metabolic versatility allows them to thrive in these niches. They play a role in biogeochemical cycles, particularly sulfur cycling, and can contribute to the formation of microbial mats.

These bacteria are typically rod-shaped or vibrioid. Their growth is dependent on the availability of light, electron donors, and carbon sources. Research into Chlorobium continues to shed light on the evolution of photosynthesis and microbial adaptation to extreme environments.