Haladaptatus paucihalophilus

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Haladaptatus paucihalophilus
Scientific classification
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H. paucihalophilus
Binomial name
Haladaptatus paucihalophilus
Savage et al 2007, emend.[1]

Haladaptatus paucihalophilus is a halophilic archaeal species, originally isolated from a spring in Oklahoma.[1] It uses a new pathway to synthesize glycine, and contains unique physiological features for osmoadaptation.[2]

Discovery[edit]

H. paucihalophilus was originally found in 2004, but was not classified as a species at the time; only the Halobacteriales were studied.[3] H. paucihalophilus was isolated from the Zodletone Spring in Oklahoma.[1] It was originally considered to have two different strains: DX253 and GY252.[1] However, the two strains were later deemed a single species, since they have a 97.7% species similarity in 16S ribosomal RNA sequence analysis.[1] To isolate H. paucihalophilus specifically, soil samples from the spring were taken and later inoculated onto a halophile-selective medium and then analyzed further after colony growth.[1] Testing was done for Gram stain, carbon source, acid production, growth at minimal salt concentration, and antibiotic sensitivity.[1] Also, PCR was performed with the primers A1F and UA1406R.[1] H. paucihalophilus was named for its ability to grow in low-salt environments (pauci meaning small, halo meaning salt, philus meaning loving).[1]

Ecology[edit]

Most species within the Halobacteriaceae can be found in environments such as springs and marshes, that contain a high salt concentration.[1] However, many of these archaeal species that have a high tolerance to salt may also exist in low-salt environments.[1] H. paucihalophilus is capable of surviving and growing within a broad range of salt concentrations, so can also be found living in low-salt environments, much like Zodletone Spring.[1]

Phylogeny[edit]

On the basis of 16S ribosomal RNA sequencing H. paucihalophilus is similar to the species Halalkalicoccus tibetensis by 89.5-90.8% with the differences concentrated at the base pairs of 1-200 and 400-800.[1] Differences with the phospholipid content in H. paucihalophilus when compared to other halophilic genera mainly constitutes the differentiation.[1]

Characterization[edit]

Morphology[edit]

H. paucihalophilus is a coccus-shaped chemoorganotroph, nonmotile, and pink-pigmented archaeal species.[1] H. paucihalophius cells are 1.2 μm in diameter with a doubling time of 12–13 hours, and are found growing as single cells or in pairs.[1] This species contains the phospholipids: phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, and phosphatidylglycerol sulfate.[1] It produces acid, grows at a pH range of 5.0-7.5, and is able to grow in salt concentrations from 0.8-5.1 M.[1]

Metabolism[edit]

The flow of carbon for H. paucihalophilus is done with the oxidative tricarboxylic acid cycle, but it does not use the reductive tricarboxylic acid cycle.[4] It uses glutamic acid, histidine, norleucine, phenylalanine, D-glucuronic acid, aesculin, trehalose, dextrin, salicin, sucrose, fructose, xylose, glucose, galactose, glycerol, citrate, pyruvate, acetate, starch, lactate, mannitol, fumarate, and malate as sources of carbon.[1] H. paucihalophilus is aerobic, so it uses oxygen as a terminal electron acceptor.[5] It is not capable using nitrate, sulfate, thiosulfate, elemental sulfur, dimethyl sulfoxide, or trimethylamine N-oxide as an electron acceptor for growth in anaerobic conditions.[1] In this species, lysine synthesis is done by the diaminopimelate pathway, the typical pathway for halophilic archaea.[4] H. paucihalophillus sets itself apart by its biosynthesis of glycine by using a mixture of three biosynthetic pathways, which are the serine hydroxymethyltransferase pathway, the threonine aldolase pathways, and the reverse of the glycine cleavage system.[4]

Genomics[edit]

The size of the genome of H. paucihalophilus is 4,317,540 total bases.[5] It contains 4,489 genes, of which 4,429 are protein-coding genes.[5] The G-C content of H. paucihalophilus is 60.5 mol%.[1]

Scientific importance[edit]

This particular halophile has an importance in the scientific field because not only can it survive high salt concentrations, but it can also tolerate low salt concentrations, making it a target species to study in the laboratory.[4] It is also the first microbe to be recognized that is able to synthesize glycine using different pathways besides the typical serine hydroxymethyltransferase pathway.[4] H. paucihalophilus is an organism to study due to its unique physiological features for osmoadaptation, which is its ability to adjust to differences in osmolarity by having salt within its cytoplasm.[2][6]

References[edit]

  1. ^ a b c d e f g h i j k l m n o p q r s t u Savage, K. N.; Krumholz, L. R.; Oren, A.; Elshahed, M.S. (2007). "Haladaptatus paucihalophilus gen. nov., sp. nov., a halophilic archaeon isolated from a low-salt, sulfide-rich spring". Journal of Systematic and Evolutionary Microbiology. 57 (1): 19–24. doi:10.1099/ijs.0.64464-0. PMID 17220434.
  2. ^ a b Youssef, N. H.; Savage-Ashlock, K. N.; McCully, A. L.; Luedtke, B.; Shaw, E. I.; Hoff, W. D.; Elshahed, M. S. (2014). "Trehalose/2-sulfotrehalose biosynthesis and glycine-betaine uptake are widely spread mechanisms for osmoadaptation in the Halobacteriales". The ISME Journal. 8 (3): 636–649. doi:10.1038/ismej.2013.165. PMC 3930309.
  3. ^ Elshahed, M.S.; Najar, F. Z.; Roe, B. A.; Oren, A.; Dewers, T. A.; Krumholz, L (2004). "Survey of archael diversity reveals an abundance of halophilic Archaea on a low-salt, sulfide- and sulfur-rich spring". Appl Environ Microbiol. 70 (4): 2230–2239. doi:10.1128/AEM.70.4.2230-2239.2004. PMC 383155.
  4. ^ a b c d e Liu, G.; Zhang, M.; Mo, T.; He, L.; Zhang, W.; Yu, Y.; Ding, W. (2015). "Metabolic flux analysis of the halophilic archaeon haladaptatus paucihalophilus". Biochemical and Biophysical Research Communications. 467 (4): 1058–1062. doi:10.1016/j.bbrc.2015.09.174. PMID 26441084.
  5. ^ a b c Markowitzl, Victor M; Chen, I-Min A.; Palaniappan, Krishna; Chu, Ken; Szeto, Ernest; Grechkin, Yuri; Ratner, Anna; Jacob, Biju; Huang, Jinghua; Williams, Peter; Huntemann, Marcel; Anderson, Iain; Marvromatis, Konstantinos; Ivanova, Natalia N.; Kyrpides, Nikos C. "Haladaptatus paucihalophilus DX253". IMG: the integrated microbial genomes database and comparative analysis system. Retrieved 26 April 2016.
  6. ^ Sleator, Roy D; Hill, Colin (2002). "Bacterial osmoadaptation: the role of osmolytes in bacterial stress and virulence". FEMS Microbiology Reviews. 26 (1): 49–71. doi:10.1111/j.1574-6976.2002.tb00598.x.

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