Haloferax alexandrinus
Haloferax alexandrinus
Contents
1 Classification
1.1 Higher order taxa
1.2 Species
2 Description and significance
3 Genome structure
4 Cell and colony structure
5 Metabolism
6 Ecology
7 Pathology
8 References
Classification
Domain (Archaea);Phylum (Euryachaeota); Class (Halobacteria); Order (Halobacteriales); family (Halobacteriaceae). Genus: Haloferax Species: Haloferax alexandrinus
Higher order taxa
Kingdom: Archaea Phylum: Euryarchaeota Class: Halobacteria Order: Halobacteriales Family: Halobacteriaceae Genus: Haloferax Species: Haloferax alexandrinus
Description and significance
Haloferax alexandrinus are characterized as an extremely halophilic (live and grow in a saline environment). Haloferax alexandrinus are red-colored cells, the color mainly being due to the presence of C50 carotenoids which its organic pigments that found in photosynthetic organisms.[1]. They are very pleomorphic which means they have different shapes, non-motile and strictly aerobic and need to live in environment of at least 10 g NaCl-1 for their growth. Also cells can grow aerobically in salty medium with ammonium chloride (halophilic archaea).[1]. Sine they live in a high concentration of NaCl medium, they don't need for sterilization procedure to prevent contamination. The concentration of the total dissolved salts increases to saturation at pH 7.2. It is noteworthy that under these extreme conditions the surface of the saltern is characterized by a reddish purple color corresponding to the growth of red halophilic members of the Achaea; other organisms cannot survive there. [1]
Genome structure
Based on the amplification of a 16S rDNA, a PCR assay was preformed to identify the species of Haloferax. For that reason and for knowing the hybridization probe, two variable regions of the 16S rDNA were selected as genus-specific primers. Result was that strains of Haloferax spp. were positive. However, species belonging to the most closely related genera were negative. In addition, the mass bloom of halophilic Archaea that develops in the El-Mallahet saltern of Alexandria City was positive using the same approach. This assay rapid method is for identifying Haloferax ssp. without the requirement of pure cultures of microorganisms in hyper saltine environments.[2] The type strain is TL6T (=JCM 13924T=DSM 18310T)
Cell and colony structure
Cell dimensions varied from 1.1 to 1.5 μm, 1.6-2.0 μm in size.[1] rod-shaped cells were 1.1 to1.5 μm and 3.5 to 4 μm in size[1] Circular shape Interesting features of cell structure. Interesting features of colony structure. It’s unique within the genus Haloferax in producing canthaxanthin. Thin layer chromatography (TLC), spectrophotometry, (EI-MS), nuclear magnetic resonance spectrometry (13C-NMR), and high performance liquid chromatography were used to investigate the core lipids of the Haloferax alexandrinus strain TM(T). It was detected the major phospholipids which were found to be phosphatidylglycerophosphate-methyl ester (PGP-Me) and phosphatidylglycerol (PG). The strain contained two glycolipids, unsulfated diglycosyl diether, and sulfated diglycosyl diether. Analysis of the non polar lipids showed the presence of 3-hydroxyechinenone, beta-carotene, gamma-carotene, lycopene, cis-astaxanthin, trisanhydrobacterioruberin, bacterioruberin isomer, and canthaxanthin. Haloferax alexandrinus strain, the polar lipids profile, was similar to those of the other species of the genus Haloferax, however, the non polar lipids (carotenoids) was markedly different.
Metabolism
Energy source(s); external electron donor(s) (=reductant source(s)); carbon source(s); oxygen classification; important molecules it produces. It gets the energy from light They are able to utilize carbon source like sugar, acetate for growth. These micro-organisms are able to utilize single carbon sources such as sugars, acetate or succinate for growth
Ecology
It can live inside a living organisms. It is very pleomorphic which means have different shapes, non-motile and strictly aerobic and requires at least 10 g NaCl l (-1) which its important for growth of the micro-organism stains gram negative. Also cells can grow aerobically in salty medium with ammonium chloride (halophilic archea).
References
[1], D. "Lipids of Haloferax Alexandrinus Strain TMT: An Extremely Halophilic Canthaxanthin-producing Archaeon." Journal of Bioscience and Bioengineering 93.1 (2002): 37-43. Print.
[2]., Asker, and Ohta Y. "Production of Canthaxanthin by Haloferax Alexandrinus under Non-aseptic Conditions and a Simple, Rapid Method for Its Extraction." Applied Microbiology and Biotechnology 58.6 (2002): 743-50. Print.
Pages edited by Safa Al Qayyar students of Dr. Lisa R. Moore, University of Southern Maine
