Proteobacteria

5 Key excerpts on "Proteobacteria"

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  Taxonomic Guide to Infectious Diseases

  Understanding the Biologic Classes of Pathogenic Organisms

  • Jules J. Berman(Author)
  • 2019(Publication Date)
  • Academic Press

    (Publisher)

  [7] . Woese had his own name for Class Proteobacteria; purple bacteria, based on their descent from a common ancestor, and capable of a photochemical reaction that yielded a photochrome that conferred a purple tinge to bacterial colonies. In addition, all members of Class Proteobacteria are Gram negative. Class Proteobacteria accounts for the majority of the Gram-negative bacteria.

  The Alpha Proteobacteria are characterized by their small size, and their intimate associations with eukaryotic cells. The Alpha Proteobacteria live as symbionts, as endosymbionts, or as intracellular parasites. This close relationship between Alpha Proteobacteria and Class Eukaryota may extend back to the very first eukaryotic cell. Based on sequence similarities between the Alpha Proteobacteria and eukaryotic mitochondria, it has been proposed that eukaryotic mitochondria evolved from an endosymbiotic member of Class Alpha Proteobacteria [Glossary Parasite ].

  There are two major subclasses of Class Alpha Proteobacteria: Rhizobiales and Rickettsiales. Class Rhizobiales contains nitrogen-fixing bacteria that live in a symbiotic relationship with plant roots. Without class Rhizobiales, life on earth, as we know it, would cease to exist. Class Rhizobiales contains two human pathogenic genera: Bartonella and Brucella.

  Alpha Proteobacteria Rhizobiales Bartonellaceae Bartonella (genus) Brucellaceae Brucella (genus)

  Genus Bartonella, formerly known as Rochalimaea, is a group of facultative intracellular organisms that produce a wide range of diseases, but which seem to share a common life cycle. The pathogenic species of Genus Bartonella are injected into humans from the bite of a blood-feeding vector: fleas, lice, sandflies, and possibly ticks. The bartonella organism infects the endothelial cells that line blood vessels. Later, the organism leaves the endothelial cell and infects erythrocytes. A blood-feeding vector extracts infected red blood cells from an infected human or from an animal reservoir. The cycle repeats.

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  The Origins of Sociable Life: Evolution After Science Studies

  • M. Hird(Author)
  • 2009(Publication Date)
  • Palgrave Macmillan

    (Publisher)

  All Proteobacteria are named by Greek letters based on their DNA 28 The Origins of Sociable Life: Evolution After Science Studies sequences. Alpha Proteobacteria proliferate, and are probably best known through their association with what scientists calls the Oxygen Holo- caust. About 3.5 billion years ago, cyanobacteria evolved and began to release oxygen as a waste product. Billions of anaerobic bacteria died, others retreated to anoxic environments such as deep sediments, some adapted metabolic mechanisms to fix oxygen to one molecule thereby removing it from contact with its other molecules, while still others evolved oxygen respiration. Chemically, respiration looks like this: Food molecule (for instance sugar) + O 2 ⇒ CO 2 + H 2 O + ATP (energy-carrying molecule) Mitochondria were once free-living independent alpha Proteobacteria. They provide animals like us with Adenosine-5'-triphosphate (ATP) – our energy source. Margulis hypothesizes that about 2.5 billion years ago, hyperthermophilic archaea and alpha Proteobacteria joined sym- biotically to form a new type of cell that was very good at acquiring energy and respiring with oxygen (more on this in Chapter 3). Because of our human cells’ symbioses with once free-living mitochondrial bac- teria, we are able to survive the ravages of the poisonous gas oxygen (of course, mitochondria are also responsible for programmed cell death, so this particular symbiosis comes with an immutable and catastrophic caveat for animals). Many nitrogen-fixers are alpha Proteobacteria, and they form symbiotic relationships with plants such as legumes. Plants require nitrogen to build proteins, RNA, DNA and other molecules (soil fertilizers contain nitrogen, which provides temporary nitrogen replenishment to the soil). The waste product from nitrogen fixation is ammonia.

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  Elements, Essence, Techniques and Applications of Microbiology

  • (Author)
  • 2014(Publication Date)
  • Academic Studio

    (Publisher)

  Bacteria are vital in recycling nutrients, with many steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. However, most bacteria have not been characterised, and only about half of the phyla of bacteria have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology. There are approximately ten times as many bacterial cells in the human flora as there are human cells in the body, with large numbers of bacteria on the skin and as gut flora. The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, and a few are beneficial. However, a few species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy and bubonic plague. The most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people a year, mostly in sub-Saharan Africa. In developed countries, antibiotics are used to treat bacterial infections and in agriculture, so antibiotic resistance is becoming common. In industry, bacteria are important in sewage ________________________ WORLD TECHNOLOGIES ________________________ treatment, the production of cheese and yogurt through fermentation, as well as in biotechnology, and the manufacture of antibiotics and other chemicals. Once regarded as plants constituting the Class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and rarely harbour membrane-bound organelles. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolved independently from an ancient common ancestor. These evolutionary domains are called Bacteria and Archaea.

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  Microbial Biotechnology

  Fundamentals of Applied Microbiology

  • Alexander N. Glazer, Hiroshi Nikaido(Authors)
  • 2007(Publication Date)
  • Cambridge University Press

    (Publisher)

  Consequently, most of the prokaryotes so far utilized for biotechnological applications belong to Bacteria. Below we list some of the groups of bacteria that are par- ticularly important in biotechnology to familiarize readers with their names and properties and to demonstrate the importance of bacterial diversity to bio- technology. For each of the organisms mentioned, we indicate the phylum to which it has been assigned using the designations provided in Figure 1.7. Deinococcus-Thermus (Phylum B4) The phylum Deinococcus-Thermus is subdivided into two orders, each of which contains a single family. Deinococcus, a representative of the first family, is an unusual organism with an extremely high resistance to ion- izing radiation. A Gram-positive chemoheterotroph, Deinococcus has been isolated from soil, ground meat, and dust. The cells are bright red or pink because of their high carotenoid content and are surrounded by an outer membrane layer, normally absent from Gram-positive bacteria. However, this outer membrane is chemically distinctive in that it does not contain the lipopolysaccharide characteristic of the outer membranes of Gram- negative bacteria. Thermus, the sole genus of the second family, consists of Gram-negative straight rods or filaments. These organisms are thermophilic, aerobic heterotrophs or chemoheterotrophs with a strictly respiratory metabolism. The Genus Thermus. Cells of Thermus strains are nonmotile. The organism was first found in hot springs in 1969 and was one of the most thermophilic Taxonomic Diversity of Bacteria with Uses in Biotechnology 27 bacteria then known. Most species have an optimum temperature for growth of 70 ◦ C to 72 ◦ C and can grow at significantly higher temperatures. Their habitat is not limited to hot springs, however; one investigator found that the best source for isolation is the hot water tanks in homes and institutions.

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  Essential Microbiology

  • Stuart Hogg(Author)
  • 2013(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  Neisseria and related Proteobacteria All members of this loose collection of bacteria are aerobic non-motile cocci, typically seen as pairs, with flattened sides where they join. Some, however, only assume this morphology during stationary growth phase. Many are found in warm-blooded animals, and some species are pathogenic. The genus Neisseria includes species responsible for gonorrhoea and meningitis in humans. 7.2.2 Other Gram-negative phyla The following section considers those Gram-negative bacteria not included in the Proteobacteria. These phyla are not closely related in the phylogenetic sense, either to each other or to the Proteobacteria. Phylum Cyanobacteria: the blue-green bacteria The Cyanobacteria are placed in volume 1 of the second edition of Bergey, along with the Archaea, the deeply branching bacteria, the ‘Deinococcus-Thermus’ group, and the green sulphur and green non-sulphur bacteria – see ‘Phylum Chlorobi (green sulphur bacteria) and phylum Chloroflexi (green non-sulphur bacteria)’ below. Members of the Cyanobacteria were once known as blue-green algae because they carry out the same kind of oxygenic photosynthesis as algae and green plants. They are the only group of prokaryotes capable of carrying 194 CH7 PROKARYOTE DIVERSITY out this form of photosynthesis; all the other groups of photosynthetic bac- teria to be discussed in this chapter carry out an anoxygenic form. When it became possible to examine cell structure in more detail with the electron microscope, it became clear that the cyanobacteria were in fact prokaryotic, and hence quite distinct from the true algae. Old habits die hard, however, and the term ‘blue-green algae’ is still encountered, particularly in the popu- lar press. Being prokaryotic, cyanobacteria do not possess chloroplasts; how- ever, they contain lamellar membranes called thylakoids, which serve as the site of photosynthetic pigments and as the location for both light-gathering and electron transfer processes.

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