Arthrobacter is a genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of bacteria that is commonly found in soil. All species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in this genus are Gram-positive
Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...

 obligate aerobe
Obligate aerobe
An obligate aerobe is an aerobic organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to oxidize substances, like sugars or fats, in order to obtain energy. During respiration, they use oxygen as the terminal electron acceptor...

s that are rods during exponential growth
Exponential growth
Exponential growth occurs when the growth rate of a mathematical function is proportional to the function's current value...

 and cocci in their stationary phase.

Colonies of Arthrobacter have a greenish metallic center on mineral salts pyridone broth
Mineral salts pyridone broth
Mineral salts pyridone broth is a selective medium for bacteria that can metabolize pyridone...

 incubated at 20 °C (68 °F). This genus is distinctive because of its unusual habit of "snapping division" in which the outer bacterial cell wall
Cell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

 ruptures at a joint (hence its name). Microbiologists refer to the type of cell division in which rods break into cocci as reversion
Reversion may refer to:*Reversion *Reversion *Reversion *Reversion *Series reversion, in mathematics*Reversion, in evolutionary biology...

. Under the microscope, these dividing cells appear as chevrons ("V" shapes). Other notable characteristics are that it can use pyridone as its sole carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 source, and that its cocci are resistant to desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately sealed container.-Science:...

 and starvation.

One species, A. crystallopoieties, has been shown to reduce hexavalent chromium
Hexavalent chromium
Hexavalent chromium refers to chemical compounds that contain the element chromium in the +6 oxidation state. Virtually all chromium ore is processed via hexavalent chromium, specifically the salt sodium dichromate. Approximately of hexavalent chromium were produced in 1985...

 levels in contaminated soil, suggesting that it may be useful in bioremediation
Bioremediation is the use of microorganism metabolism to remove pollutants. Technologies can be generally classified as in situ or ex situ. In situ bioremediation involves treating the contaminated material at the site, while ex situ involves the removal of the contaminated material to be treated...


Arthrobacter chlorophenolicus sp. nov., a species capable of degrading high concentrations of 4-chlorophenol, may also be useful in bioremediation. Arthrobacter sp. strain R1 has been shown to grow on a variety of aromatic compounds, including homocyclic compounds, such as hydroxybenzoates, as well as N-heterocycles, including pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...

 and picoline
Picoline refers to three different methylpyridine isomers, all with the chemical formula C6H7N and a molar mass of 93.13 g mol−1. All three are colourless liquids at room temperature and pressure and are miscible with water and most organic solvents...


Arthrobacter sp H65-7 produces the enzyme inulase II that converts inulin
Inulins are a group of naturally occurring polysaccharides produced by many types of plants. They belong to a class of fibers known as fructans. Inulin is used by some plants as a means of storing energy and is typically found in roots or rhizomes...

 into difructose anhydride (DFA). DFA is a promising nutrient for fighting osteoporis, because it helps absorption of calcium in the intestines.

External links

  • Comparative Analysis of Arthrobacter Genomes (at DOE's
    United States Department of Energy
    The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...

     IMG system
    Integrated Microbial Genomes System
    The Integrated Microbial Genomes is a genome browsing and annotation system developed by the DOE-Joint Genome Institute. IMG contains all the draft and complete microbial genomes sequenced by the DOE-JGI integrated with other publicly available genomes...

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