Purple sulfur bacteria Purple sulfur bacteria The purple sulfur bacteria (PSB) are part of a group of Proteobacteria 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 well, some species can use H, Fe, or NO) as the electron donor in
Cavalier-Smith's system of classification to plants. By 1959, Robert Harding Whittaker (1920–1980) proposed that fungi, which were formerly classified as plants, be given their own kingdom. His four kingdoms of life were: Whittaker subdivided the Protista into two subkingdoms: Bacteria are fundamentally different from the eukaryotes (plants, animals, fungi, amebas, protozoa, and chromista). Eukaryotes have cell nuclei, bacteria do not. In 1969, Robert Whittaker elevated the bacteria to the status of kingdom. His new classification system divided the living world into five kingdoms: The kingdom Monera can be divided into two distinct groups: eubacteria and archaebacteria. In 1977 Carl Woese and George E. Fox