Gammaproteobacteria in the context of "Enterobacteriaceae"

In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic compounds (e.g., hydrogen gas, hydrogen sulfide) or ferrous ions as a source of energy, rather than sunlight, as in photosynthesis. Chemoautotrophs, organisms that obtain carbon from carbon dioxide through chemosynthesis, are phylogenetically diverse. Groups that include conspicuous or biogeochemically important taxa include the sulfur-oxidizing Gammaproteobacteria, the Campylobacterota, the Aquificota, the methanogenic archaea, and the neutrophilic iron-oxidizing bacteria.

Many microorganisms in dark regions of the oceans use chemosynthesis to produce biomass from single-carbon molecules. Two categories can be distinguished. In the rare sites where hydrogen molecules (H₂) are available, the energy available from the reaction between CO₂ and H₂ (leading to production of methane, CH₄) can be large enough to drive the production of biomass. Alternatively, in most oceanic environments, energy for chemosynthesis derives from reactions in which substances such as hydrogen sulfide or ammonia are oxidized. This may occur with or without the presence of oxygen.

Pseudomonadota (synonym "Proteobacteria") is a major phylum of gram-negative bacteria. They include pathogenic and free-living (non-parasitic) genera. The phylum comprises six classes Acidithiobacillia, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Hydrogenophilia, and Zetaproteobacteria. The Pseudomonadota are widely diverse, with differences in morphology, metabolic processes, relevance to humans, and ecological influence.

Lamellibrachia is a genus of tube worms related to the giant tube worm, Riftia pachyptila. They live at deep-sea cold seeps where hydrocarbons (oil and methane) leak out of the seafloor, and are entirely reliant on internal, sulfide-oxidizing bacterial symbionts for their nutrition. The symbionts, gammaproteobacteria, require sulfide and inorganic carbon (carbon dioxide). The tube worms extract dissolved oxygen and hydrogen sulfide from the sea water with the crown of plumes. Species living near seeps can also obtain sulfide through their "roots", posterior extensions of their body and tube. Several sorts of hemoglobin are present in the blood and coelomic fluid to bind to the different components and transport them to the symbionts.

L. luymesi provides the bacteria with hydrogen sulfide and oxygen by taking them up from the environment and binding them to a specialized hemoglobin molecule. Unlike the tube worms that live at hydrothermal vents, L. luymesi uses a posterior extension of its body called the root to take up hydrogen sulfide from the seep sediments. L. luymesi may also help fuel the generation of sulfide by excreting sulfate through its root into the sediments below the aggregations.

Beggiatoa is a genus of Gammaproteobacteria belonging to the order Thiotrichales, in the Pseudomonadota phylum. These bacteria form colorless filaments composed of cells that can be up to 200 μm in diameter, and are one of the largest prokaryotes on Earth. Beggiatoa are chemolithotrophic sulfur-oxidizers, using reduced sulfur species as an energy source. They live in sulfur-rich environments such as soil, both marine and freshwater, in the deep sea hydrothermal vents, and in polluted marine environments. In association with other sulfur bacteria, e.g. Thiothrix, they can form biofilms that are visible to the naked eye as mats of long white filaments; the white color is due to sulfur globules stored inside the cells.

Acidithiobacillia is a class of the phylum Pseudomonadota ("Proteobacteria"). Its type order, the Acidithiobacillales, was formerly classified within the Gammaproteobacteria, and comprises two families of sulfur-oxidising autotrophs, the Acidithiobacillaceae and the Thermithiobacillaceae, which in turn include the genera Acidithiobacillus and Thermithiobacillus. The Acidithiobacillales are an order of bacteria within the class Acidithiobacillia and comprises the genera Acidithiobacillus and Thermithiobacillus. Originally, both were included in the genus Thiobacillus, but they are not related to the type species, which belongs to the Betaproteobacteria.

Acidithiobacilia is part of the acidophilic bacteria family. Acidithiobacilia's metabolic activity is important because it is relied on for an approach for metal recovery from ores, called microorganism-mediated biohydrometallurgy. Acidithiobacilia and family of bacteria are active players in the sulfur and iron biogeochemical cycles in extremely acidic environments and drivers of the leaching of mineral ores contributing to acid rock/mine drainage and industrial bioleaching.

The purple sulfur bacteria (PSB) are part of a group of Pseudomonadota capable of photosynthesis, collectively referred to as purple bacteria. They are anaerobic or microaerophilic, and are often found in stratified water environments including hot springs, stagnant water bodies, as well as microbial mats in intertidal zones. Unlike plants, algae, and cyanobacteria, purple sulfur bacteria do not use water as their reducing agent, and therefore do not produce oxygen. Instead, they can use sulfur in the form of sulfide or thiosulfate as the electron donor in their photosynthetic pathways. Some species can use H₂, Fe, or NO₂ as well. The sulfur is oxidized to produce granules of elemental sulfur. This, in turn, may be oxidized to form sulfuric acid.

The purple sulfur bacteria are largely divided into two families, the Chromatiaceae and the Ectothiorhodospiraceae, which produce internal and external sulfur granules respectively, and show differences in the structure of their internal membranes. They make up part of the order Chromatiales, included in the Gammaproteobacteria. The genus Halothiobacillus is also included in the Chromatiales, in its own family, but it is not photosynthetic.