Survey of Genomes - Halobacterium NRC-1
Zoe Ceballos introduces us to a member of the Domain Archaea that lives in a very extreme habitat - salt at saturating concentration (> 5 molar). Halobacterium and its obligate halophile relatives have evolved a salt-dependent lifestyle, unlike virtually all other cellular lifeforms.
genus of Halobacteriaceae. The Halobacterium species is actually not a bacteria, however, it belongs to
the archea domain. Halobacterium was originally studied in the 1960s, brine shrimp, who are filter
feeders, would consume the Halobacterium, in turn, flamingos would eat the brine shrimp, giving them
the pigment that they are. The genus Halobacterium ("salt" or "ocean bacterium") consists of several
species of the Archaea with an aerobic metabolism which requires an environment with a high
concentration of salt; many of their proteins will not function in low-salt environments. These organisms
can be found in the Great Salt Lake, the Dead Sea, and other waters with high salt concentrations.
Halobacterium is used for postgenomic analysis. Halobacterium is also used as biomediation
agents, they have been used for soil remediation . Some strains of Halobacterium are being explored for
medical applications for their radiation-resistance mechanisms. Bacterioruberin is a carotenoid pigment
found in Halobacterium which decreases the bacteria’s sensitivity to UV radiation and other types of
radiation. It has been shown in studies that the absence of bacterioruberin increases the sensitivity of
the bacterium to oxidative DNA-damaging agents. Halobacterium also exhibits high intracellular
concentrations of potassium chloride which has also been shown to confer radiation resistance.
Halobacterium are also being explored for the pharmaceutical applications of bioactive compounds they
produce, including anticancer agents, antimicrobial biosurfactancts, and antimicrobial metabolites. They
possess genes for DNA replication as well.
The genome is 2,571,010 base pairs long, there are 3 circular strands, the large chromosome is
2,014,239 base pairs long while the other two mini chromosomes are 191,346 and 365,425 base pair
long respectively. The minichromosomes are A-T rich, they have a GC content of 58% and 59% compared
to the large chromosome which possesses a GC content of 68%.
Balakrishnan, Arjun, et al. “Halobacterial Nano Vesicles Displaying Murine Bactericidal Permeability-
Increasing Protein Rescue Mice from Lethal Endotoxic Shock.” Nature News, Nature Publishing Group,
20 Sept. 2016, www.nature.com/articles/srep33679.
Evans, Jessica J., et al. “Divergent Roles of RPA Homologs of the Model Archaeon Halobacterium
Salinarum in Survival of DNA Damage.” MDPI, Multidisciplinary Digital Publishing Institute, 20 Apr. 2018,
Halobacterium Sp. NRC-1.” Microbewiki, microbewiki.kenyon.edu/index.php/Halobacterium_sp._NRC-1.
Kennedy, Sean P., et al. “Understanding the Adaptation of Halobacterium Species NRC-1 to Its Extreme
Environment through Computational Analysis of Its Genome Sequence.” Genome Research, Cold Spring
Harbor Lab, 1 Jan. 1970, genome.cshlp.org/content/11/10/1641.full.
Ng, Wailap Victor, et al. “Genome Sequence of Halobacterium Species NRC-1.” PNAS, National Academy
of Sciences, 24 Oct. 2000, www.pnas.org/content/97/22/12176.