Arthrobacter

Arthrobacter
Arthrobacter chlorophenolicus
Scientific classification
Kingdom:	Bacteria
Phylum:	Actinobacteria
Class:	Actinobacteria
Order:	Actinomycetales
Family:	Micrococcaceae
Genus:	Arthrobacter Conn & Dimmick, 1947
Species
Arthrobacter agilis[1] Arthrobacter albidus[1] Arthrobacter albus[1] Arthrobacter alkaliphilus[1] Arthrobacter alpinus[1] Arthrobacter antarcticus[1] Arthrobacter ardleyensis[1] Arthrobacter arilaitensis[1] Arthrobacter aurescens[1] Arthrobacter bambusae[1] Arthrobacter bergerei[1] Arthrobacter castelli[1] Arthrobacter chlorophenolicus[1] Arthrobacter citreus[1] Arthrobacter creatinolyticus[1] Arthrobacter cryoconiti[1] Arthrobacter cryotolerans[1] Arthrobacter crystallopoietes[1] Arthrobacter cumminsii[1] Arthrobacter cupressi[1] Arthrobacter defluvii[1] Arthrobacter echigonensis[1] Arthrobacter equi[1] Arthrobacter enclensis[1] Arthrobacter flavus[1] Arthrobacter gandavensis[1] Arthrobacter gangotriensis[1] Arthrobacter globiformis[1] Arthrobacter gyeryongensis[1] Arthrobacter halodurans[1] Arthrobacter histidinolovorans[1] Arthrobacter humicola[1] Arthrobacter ilicis[1] Arthrobacter kerguelensis[1] Arthrobacter koreensis[1] Arthrobacter liuii[1] Arthrobacter livingstonensis[1] Arthrobacter luteolus[1] Arthrobacter methylotrophus[1] Arthrobacter monumenti[1] Arthrobacter mysorens[1] Arthrobacter nanjingensis[1] Arthrobacter nasiphocae[1] Arthrobacter nicotianae[1] Arthrobacter nicotinovorans[1] Arthrobacter niigatensis[1] Arthrobacter nitroguajacolicus[1] Arthrobacter oryzae[1] Arthrobacter oxydans[1] Arthrobacter parietis[1] Arthrobacter pascens[1] Arthrobacter phenanthrenivorans[1] Arthrobacter pigmenti[1] Arthrobacter pityocampae[1] Arthrobacter polychromogenes[1] Arthrobacter protophormiae[1] Arthrobacter psychrochitiniphilu[1] Arthrobacter psychrolactophilus[1] Arthrobacter psychrophenolicus[1] Arthrobacter ramosus[1] Arthrobacter rhombi[1] Arthrobacter roseus[1] Arthrobacter russicus[1] Arthrobacter sanguinis[1] Arthrobacter scleromae[1] Arthrobacter siccitolerans[1] Arthrobacter soli[1] Arthrobacter stackebrandtii[1] Arthrobacter subterraneus[1] Arthrobacter sulfonivorans[1] Arthrobacter sulfureus[1] Arthrobacter tecti[1] Arthrobacter tumbae[1] Arthrobacter uratoxydans[1] Arthrobacter ureafaciens[1] Arthrobacter viscosus[1] Arthrobacter woluwensis[1]

Arthrobacter (from the Greek, "jointed small stick”) is a genus of bacteria that is commonly found in soil. All species in this genus are Gram-positive obligate aerobes that are rods during exponential growth and cocci in their stationary phase.

Colonies of Arthrobacter have a greenish metallic center on mineral salts pyridone broth 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 ruptures at a joint (hence its name). Microbiologists refer to the type of cell division in which rods break into cocci as reversion. Under the microscope, these dividing cells appear as chevrons ("V" shapes). Other notable characteristics are that it can use pyridone as its sole carbon source, and that its cocci are resistant to desiccation and starvation.

In a bioprocess, one requires two important things: cells and media.

The production of L-glutamate can utilise a large variety of bacterial strains, from many different genera and type. In the past, bacteria from the Brevibacterium, Arthrobacter, Microbacterium and Corynebacterium genera have been exploited for this purpose. The most commonly-used bacterial strain today, however, is Corynebacterium glutamicum, previously known as Micrococcus glutamicum. As a non-pathogenic coryneform bacterium, C. glutamicum is a popular choice of bacteria for several other amino acids as well.

As for growth media, the choices are many. A major concern of large-scale manufacturers is the cost of the media, and so they prefer to use sugar sources such as cane or beet molasses, starch hydrolysates from corn or cassava tubers, or even tapioca. The choice of sugar source essentially depends on whatever is most readily available. Generally, a manufacturer will use a sugar source from a regional plant source. Along with sugar, ammonia and ammonium salts are added as a nitrogen source. The vitamins, minerals, and some other types of nutrients can be easily and cheaply provided by adding corn steep liquour.

One species, A. crystallopoietes, has been shown to reduce hexavalent chromium levels in contaminated soil, suggesting that it may be useful in bioremediation.^[2]

Arthrobacter chlorophenolicus sp. nov., a species capable of degrading high concentrations of 4-chlorophenol, may also be useful in bioremediation.^[3] Arthrobacter sp. strain R1 (American Type Culture Collection strain number 49987) has been shown to grow on a variety of aromatic compounds, including homocyclic compounds, such as hydroxybenzoates, as well as N-heterocycles, including pyridine and picoline.^[4] This bacterium produces a dark pigment when grown on pyridine, but not simple substrates, such as succinic acid.

Arthrobacter crystallopoietes produces a pigment when grown on 2-pyridone (right) but not when grown on succinic acid (left).

Arthrobacter sp H65-7 produces the enzyme inulase II that converts inulin into difructose anhydride (DFA). DFA is a promising nutrient for fighting osteoporis, because it helps absorption of calcium in the intestines.

The enzyme Alu obtained from Arthrobacter luteus is able to cleave Alu sequences in human DNA, causing the kind of gene sequence to be named after the enzyme. Alu are a group of moderately repetitive gene sequences (300bp in length). Alu sequences make up 6-8% of the human genome.^[5]

References

1. LPSN bacterio.net
2. F.A.O Camargo, F.M. Bento, B.C. Okeke, and W.T. Frankenberger (2003). "Hexavalent chromium reduction by an actinomycete, Arthrobacter crystallopoietes ES 32". Biological Trace Element Research 97 (2): 183–194. doi:10.1385/BTER:97:2:183. PMID 14985627.
3. K Westerberg, AM Elvang, E Stackebrandt and JK Jansson (2000). "Arthrobacter chlorophenolicus sp. nov., a new species capable of degrading high concentrations of 4-chlorophenol". International Journal of Systematic and Evolutionary Microbiology 50: 2083–2092. doi:10.1099/00207713-50-6-2083. PMID 11155983.
4. O'Loughlin, E. J., G.K. Sims, and S.J. Traina (1999). "Biodegradation of 2-methyl, 2-ethyl, and 2-hydroxypyridine by an arthrobacter sp. isolated from subsurface sediment". Biodegradation 10 (2): 93–104. doi:10.1023/A:1008309026751. PMID 10466198.
5. Marks A. Basic Medical Biochemistry: a Clinical Approach 3ed, p. 248.

External links

• Arthrobacter Genome Projects (from Genomes OnLine Database)
• Comparative Analysis of Arthrobacter Genomes (at DOE's IMG system)