Persephonella marina
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''Persephonella marina'' is a
Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...
, rod shaped bacteria that is a member of the '' Aquificota'' phylum. Stemming from Greek, the name Persephonella is based upon the mythological goddess
Persephone In ancient Greek mythology and religion, Persephone ( ; gr, Περσεφόνη, Persephónē), also called Kore or Cora ( ; gr, Κόρη, Kórē, the maiden), is the daughter of Zeus and Demeter. She became the queen of the underworld after ...
. Marina stems from a Latin origin, meaning "belonging to the sea". It is a
thermophile A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...
with an obligate
chemolithoautotrophic A lithoautotroph is an organism which derives energy from reactions of reduced compounds of mineral (inorganic) origin. Two types of lithoautotrophs are distinguished by their energy source; photolithoautotrophs derive their energy from light while ...
metabolism. Growth of ''P. marina'' can occur in pairs or individually, but is rarely seen aggregating in large groups. The organism resides on sulfidic chimneys in the deep ocean and has never been documented as a pathogen.


Discovery

''Persephonella marina'' was first isolated in 1999 using MSH medium, a medium containing 29 g NaCl, 2 g NaOH, 0.5 g KCl, 1.36 g MgCl2•6H2O, 7 g MgSO4•7H2O, 2 g Na2S2O3•5H2O, 0.4 g CaCl2•2H2O, 0.2 g NH4Cl, 0.3 g K2HPO4•3H2O and 10 ml of a trace-element stock solution, with a gas phase containing twenty parts carbon dioxide, one part oxygen, and twenty six parts hydrogen gas. Initial isolation was provided by a sample obtained from a depth of 2,507 meters on a sulfidic chimney. This particular sulfidic chimney was named "Q-Vent" and is located at a
latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...
of 9° North and a
longitude Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter l ...
of 104° West in a region called the
East Pacific Rise The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located along ...
. The environment in which ''P. marina'' was obtained was too harsh for humans due to the excessive temperature (133 °C with spikes up to 170 °C) and extreme pressure. Due to these harsh conditions a submarine was used for extraction of the samples.


Genomics

''Persephonella marina'' has a genome size of 1.9 mega (10^9) base pairs with 2,048 encoded genes. The organism contains a GC content of 37%. This is unusually low for thermophilic organisms which typically contain high amounts of GC bonds to prevent DNA denaturation. The organism's closest phylogenetic neighbor was isolated under the same study and was named '' Persephonella guaymasensis''. It shares 96% of its genome with ''P. marina.'' Other similar genomes include: ''Hydrogenothermus marinus'' (94.5% similarity), and '' Aquifex pyrophilius'' (85% similarity).


Characterization


Metabolism

''Persephonella marina'' is an obligate
chemolithoautotroph A lithoautotroph is an organism which derives energy from reactions of reduced compounds of mineral (inorganic) origin. Two types of lithoautotrophs are distinguished by their energy source; photolithoautotrophs derive their energy from light while ...
. It utilizes three primary electron donors: elemental
sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
(S°), hydrogen gas (H2), and thiosulfate (S2O32−). Oxygen and
nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...
act as electron acceptors for ''P. marina.'' In the lab, when ''P. marina'' was exposed to high amounts of elemental
sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
, the organism produced an excess of
sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...
. When exposed to microaerophilic conditions as found near deep sea
hydrothermal vent A hydrothermal vent is a fissure on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspot ...
s, P. marina was able to perform
aerobic respiration Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Cellular respiration may be des ...
. Oxygen is not the primary electron acceptor and can only be utilized when exposed to oxygen in this microaerophilic environment.


Growth Conditions

''Persephonella marina'' is a thermophilic organism that grows optimally in a temperature range of 55 to 80 degrees
Celsius The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The ...
. The organism does show the ability to survive at
hyperthermophilic A hyperthermophile is an organism that thrives in extremely hot environments—from 60 °C (140 °F) upwards. An optimal temperature for the existence of hyperthermophiles is often above 80 °C (176 °F). Hyperthermophiles are often within the doma ...
conditions as it was first isolated in water temperatures of 133 degrees
Celsius The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The ...
. ''P. Marina'' does not have the ability to form
spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s, highlighting the presence of a process that keeps DNA and essential proteins stable at extremely high temperatures commonly found near hydrothermal vents. Once cultured the organism was found to be able to grow in
halophilic The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, ...
conditions between 2 and 4 1/2 percent NaCl but grows optimally at 2 1/2 percent NaCl. ''P. Marina'' possesses a wide range of pH in which it can grow, spanning from 4.7 to 7.5. In optimal growth conditions, the doubling time for ''P. Marina'' is around 5 hours.


Glucosylglycerate and α(1,6)glucosyl-α-(1,2)glucosylglycerate

''Persephonella marina'' was used as a model organism for the characterization of genes and enzymes for the synthesis of glucosylglycerate found for the first time in a thermophile. Glucosylglycerate protects the microbe from thermal stresses and helps in adaptation to starvation conditions. This is of great importance to scientists who wish to study extremophiles. This solute is also important in the advancement of biotechnology. When tested in lab, glucosylglycerate increased the melting temperature of essential enzymes in basic metabolic pathways. It has an effect on a microbe's ability to withstand high-pressure environments. This rare solute has only been found in a few other
halophilic The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, ...
bacteria and one Archaeon, but has never been encountered in a hyperthermophile such as ''P. marina.'' It is also worth noting that ''P. marina'' has led to the discovery of α(1,6)glucosyl-α-(1,2)glucosylglycerate by proton NMR and is still currently under study. Both of these solutes are disaccharide heterosides which are extremely rare in
thermophile A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...
s. Both are important in osmotic adaptation in microbes as well. With many questions to be answered about these two solutes, further research could benefit biotechnology in application to production of things such as
food preservatives Food preservation includes processes that make food more resistant to microorganism growth and slow the redox, oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that in ...
and textiles. Also, for scientists who are looking to further answer why and how hyperthermophiles survive, these two solutes could help fill in the missing pieces of the puzzle.


References


External links


Type strain of ''Persephonella marina'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{DEFAULTSORT:Persephonella marina Aquificota Bacteria described in 2002