Chromohalobacter Salexigens

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A Microbial Biorealm page on the genus Chromohalobacter Salexigens

Classification

Higher order taxa

Bacteria; Proteobacteria; Gammaproteobacteria; Oceanospirillales; Halomonadaceae; Chromohalobacter;

"Chromohalobacter salexigens"[[1]]

NCBI: Taxonomy Genome

Species

C. salexigens

Description and significance

"C. salexigens" is a gram negative marine bacterium that lives in hypersaline environments. It was isolated from the island of Bonaire, Netherlands Antilles [6].This bacterium is a moderate halophile, with a broad salinity range. C. salexigens is very flexible in that its salt requirements can be met by ions of other salts such as potassium, rubidium, ammonium, bromide, and others [2]. It is an aerobic chemoorganotroph. It can live in a variety of saline conditions but their optimum concentration is between 2-2.5M [6].

Genome structure

DNA Bases: 3696649

Chromosome Type: Circular

Total Genes: 3403

Protein Coding Genes: 3319
RNA Genes:              84
Pseudo Genes:           21

Cell structure and metabolism

The ability of C. salexigens to survive in a broad range of salinity, makes it a euryhaline bacterium [6]. "C. salexigens" can be considered extremophiles because they are able to survive in hypersaline conditions due to its osmoregulatory mechanisms, such as its production of ectoine. Its versatile metabolism allows for fast growth because of its ability to use a variety of simple carbon compounds as both its carbon and energy source. This bacterium compared, to other organisms that can live in high saline environments, has a more acidic amino acids that enable it to produce the organic solute, ectoine [7].

Ecology

Interactions between C. salexigens and other bacterium such as various strands of Salmonella allow for salinity tolerance modulation. In other words, this bacterium allows for other organisms to exist in environments they would otherwise not be able to cope with [4].

"C. salexigens" have the eight- gene cluster in order to from Isethionate from taurine, one of the simple compounds that this bacterium uses for its carbon and energy source. The formation of isethionate is used as nutrients for bacterium, "C. salexigens" create a reserve to use as nutrients for other bacterium [8].

Pathology

Current research indicates that C. salexigens is not known to be pathogenic.

Application to Biotechnology

In response to salt and temperature stress C. salexigens produces and stores various solutes. Some solutes, namely hydroxyectoine, are used in thermoregulation processes that protect C. salexigens from extreme temperatures. [3]

Current Research

Ectoine biosynthesis pathways[[2]]

"C. salexigens" are used as the model organism to test osmoadaptation, ectoine is a natural compound found in this bacterium and "C. salexigens" are osmoadaptive because of its' ability to biosynthesize ectoine [7].

Scientists are researching mutant C. salexigens bacterium that synthesize ectoine. C. Salexigens mutants can be used to produce N(gamma)-acetyl-2,4-diaminobutyrate (NADA). When mutants are placed in conjunction with the bacterium Salmonella Enterica Serovar Typhimurium, salinity stress typically present in this form of Salmonella ceased to persist. [4]

In other research, C. Salexigens is being investigated to better understand its long-term response to salinity stress regarding membrane modulation. Ectoine-deficient strains of C. salexigens are unable to cope with salinity stress and undergo extensive membrane changes. The addition of ectoine to these deficient strains, however, allows these bacterium to maintain a salinity responsive membrane. [5]

References

[1] Stothard P, Van Domselaar G, Shrivastava S, et. al. 2005. BacMap: an interactive picture atlas of annotated bacterial genomes. Nucleic Acids Res 33:D317-D320

[2] O'Connor K, Csonka LN. 2003. Salt Requirements of C. Salexigens. Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392.

[3] Garcia-Estepa R, Argandona M, Reina-Bueno M, et. al. 2006. Thermoprotection of C. Salexigens. Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Spain.

[4] Garcia-Estepa R, Canovas D, Iglesias-Guerra F, et. al. 2006. Osmoprotection of Salmonella Enterica. Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Spain.

[5] Vargas C, Kallimanis A, Koukkou AI, et. al. 2005. NADA, the Precursor to Ectoine. Department of Microbiology and Parasitology, University of Seville, Spain.

[6] Oren, A, Larimer F, Richardson P, et al. 2005. How to be moderately halophilic with broad salt tolerance. Extremophiles. 9:275-279.

[7] Ates O, Toksoy E, Arga K. 2011. Genome-scale reconstruction of metabolic network for a halophilic extremophile Chromohalobacter salexigens DSM 3043. BMC Systems Biology 5:12.

[8] Krejcik Z, Hollemeyer K, Smits T, Cook A. 2010. Isethionate formation from taurine in CHromohalobacter salexigens: purification of sulfoacetaldehyde reductase. Microbiology 156: 1547-1555.

Edited by Chris Wittrock, a student of Rachel Larsen and Kit Pogliano

Revised by Sydney Rodman of Randolph-Macon College