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paucihalophilus
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| 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]
H. paucihalophilus was originally found in 2004 by Mostafa Elshahed et al, but was not classified as a species at the time; only the Halobacteriales were studied. [3] Kristen N. Savage et al, isolated H. paucihalophilus from the Zodletone Spring located in Oklahoma.[1] It was originally considered to have two different strains: DX253 and GY252[1]. However, the two strains were later deemed together as a single species since they have a 97.7% species similarity in 16S ribosomal RNA sequence analysis.[1] In order to isolate H. paucihalophilus specifically, soil samples from the spring were taken and later inoculated onto a halophile selected medium and then analyzed further after colonial growth.[1] Testing was done for Gram reaction, 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]
Most species within Halobacteriaceae can be found in environments, such as springs and marshes, that contain a high salt concentration.[1] However, it has been suggested that many of these archaeal species that have a high tolerance to salt can also exist in low-salt environments.[1] H. paucihalophilus is capable of surviving and growing within a broad range of salt concentrations, therefore it can also be found living in low-salt environments, much like Zodletone Spring.[1]
On the basis of 16S ribosomal RNA sequencing Haladaptatus 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 is what mainly constitutes differentiation.[1]
Haladaptatus paucihalophilus is a cocci-shaped chemoorganotroph, non-motile, and pink pigmented archaeal species.[1] H. paucihalophius cells are 1.2 micrometers in diameter with a doubling time of 12-13 hours and are found growing as single cells or in pairs of two.[1] This speceis 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 it is able to grow in a wide range of salt concentrations from 0.8-5.1M.[1]
The flow of carbon for Haladaptatus paucihalophilus is done with the oxidative tricarboxylic acid cycle, however 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. paucihalophilusisaerobic so it uses oxygen as a terminal electron acceptor [5]. It is not capable using nitrate, sulfate, thiosulfate, elemental sulfur, dimethyl sulfoxide (DMSO), or trimethylamine N-oxide (TMAO) 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 biosynthesisofglycine 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]
The size of the genomeofH. paucihalophilus is 4,317,540 total bases.[5] It contains 4,489 genes that of which 4,429 are protein coding genes.[5] The G-C contentofH. paucihalophilus is 60.5 mol%. [1]
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 lab[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.[6][2]
