Deltaproteobacteria

Deltaproteobacteria are a major class within the phylum Proteobacteria. They are Gram-negative and metabolically diverse, with many members adapted to anaerobic or microaerophilic environments. The group includes several ecologically important lineages, including sulfate-reducing bacteria and a variety of predatory and social bacteria.

A defining feature of many Deltaproteobacteria is their tendency to use sulfate or sulfur compounds as terminal electron acceptors in anaerobic respiration. Sulfate-reducing bacteria, such as Desulfovibrio, Desulfotomaculum, and Desulfobacter species, oxidize organic compounds or hydrogen while reducing sulfate to hydrogen sulfide. These organisms play key roles in the sulfur cycle and are common in marine sediments, freshwater sediments, and oil reservoirs. Other members can couple metabolism to the reduction of sulfur compounds, elemental sulfur, or metals, contributing to biogeochemical cycling and, in some cases, bioremediation.

The class also includes notable predatory and social bacteria. Bdellovibrio and related species are obligate predators of Gram-negative bacteria, invading and consuming them from the periplasm. Myxobacteria, such as Myxococcus species, are social organisms that prey on other bacteria and form multicellular fruiting bodies under nutrient limitation, marking a distinct lifestyle within the group.

Taxonomically, Deltaproteobacteria encompass several orders, including Desulfovibrionales, Desulfobacterales, Desulfuromonadales, as well as Bdellovibrionales and Myxococcales. Taxonomic placement has evolved with molecular analyses, reflecting the diversity and metabolic breadth of the group.