Nanobacterium

Nanobacterium

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Nanobacterium is the unit or member name of a proposed class of living organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...

s, specifically cell-walled
Cell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

 microorganisms with a size much smaller than the generally accepted lower limit size for life (about 200 nanometre
Nanometre
A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter...

s for bacteria). Originally based on observed nano-scale structures in geological formations (including one meteorite), the status of nanobacteria is controversial, with some researchers suggesting they are a new class of living organisms capable of incorporating radiolabeled uridine
Uridine
Uridine is a molecule that is formed when uracil is attached to a ribose ring via a β-N1-glycosidic bond.If uracil is attached to a deoxyribose ring, it is known as a deoxyuridine....

, and others attributing to them a simpler, abiotic nature. One skeptic dubbed them "the cold fusion
Cold fusion
Cold fusion, also called low-energy nuclear reaction , refers to the hypothesis that nuclear fusion might explain the results of a group of experiments conducted at ordinary temperatures . Both the experimental results and the hypothesis are disputed...

 of microbiology", in reference to a notorious episode of erroneous science.

The term "calcifying nanoparticles" (CNPs) has also been used as a conservative name regarding their possible status as a life form. The most recent research tends to agree that these structures exist, and probably replicate in some way. Their status as living entities is still debated, though some researchers claim that the case that they are nonliving crystalline particles is conclusively proven. In medicine, they have been implicated in the formation of both kidney stones and arterial plaque.

1981–2000


In 1981 Torella and Morita described very small cells called ultramicrobacteria
Ultramicrobacteria
Ultramicrobacteria are bacteria that are considerably smaller than normal bacterial cells and are 0.3 to 0.2 micrometres in diameter. This term was first used in 1981, to refer to cocci in seawater that were less than 0.3 μm in diameter. These cells have also been recovered from soil and appeared...

. Defined as being smaller than 300 nm, by 1982 MacDonell and Hood found that some could pass through a 200 nm membrane. Early in 1989, geologist Robert L. Folk found what he later identified as nannobacteria (written with double "n"), that is, nanoparticles isolated from geological specimens in travertine
Travertine
Travertine is a form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan, and cream-colored varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot...

 from hot springs of Viterbo
Viterbo
See also Viterbo, Texas and Viterbo UniversityViterbo is an ancient city and comune in the Lazio region of central Italy, the capital of the province of Viterbo. It is approximately 80 driving / 80 walking kilometers north of GRA on the Via Cassia, and it is surrounded by the Monti Cimini and...

, Italy. Initially searching for a bacterial cause for travertine deposition, scanning electron microscope
Scanning electron microscope
A scanning electron microscope is a type of electron microscope that images a sample by scanning it with a high-energy beam of electrons in a raster scan pattern...

 examination of the mineral where no bacteria were detectable revealed extremely small objects which appeared to be biological. His first oral presentation elicited what he called "mostly a stony silence", at the 1992 Geological Society of America
Geological Society of America
The Geological Society of America is a nonprofit organization dedicated to the advancement of the geosciences. The society was founded in New York in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hitchcock, John R. Proctor and Edward Orton and has been headquartered at 3300 Penrose...

's annual convention. He proposed that nanobacteria are the principal agents of precipitation of all minerals and crystals on Earth formed in liquid water, that they also cause all oxidation of metals, and that they are abundant in many biological specimens.

In 1996, NASA scientist David McKay
David S. McKay
David S. McKay is Chief Scientist for Astrobiology at the Johnson Space Center. McKay was the first author of a scientific paper postulating past life on Mars on the basis of evidence in Martian meteorite ALH84001 found in Antarctica. This paper has become one of the most heavily cited papers in...

 published a study suggesting the existence of nanofossils — fossils of Martian nanobacteria — in ALH84001
ALH84001
Allan Hills 84001 is a meteorite that was found in Allan Hills, Antarctica on December 27, 1984 by a team of U.S. meteorite hunters from the ANSMET project. Like other members of the group of SNCs , ALH 84001 is thought to be from Mars. However, it does not fit into any of the previously...

, a meteorite originating from Mars and found in Antarctica.

Nanobacterium sanguineum was proposed in 1998 as an explanation of certain kinds of pathologic calcification
Calcification
Calcification is the process in which calcium salts build up in soft tissue, causing it to harden. Calcifications may be classified on whether there is mineral balance or not, and the location of the calcification.-Causes:...

 (apatite
Apatite
Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, chlorapatite and bromapatite, named for high concentrations of OH−, F−, Cl− or Br− ions, respectively, in the crystal...

 in kidney stone
Kidney stone
A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine...

s) by Finnish
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

 researcher Olavi Kajander and Turkish researcher Neva Ciftcioglu, working at the University of Kuopio in Finland. According to the researchers the particles self-replicated
Self-replication
Self-replication is any behavior of a dynamical system that yields construction of an identical copy of that dynamical system. Biological cells, given suitable environments, reproduce by cell division. During cell division, DNA is replicated and can be transmitted to offspring during reproduction...

 in microbiological culture
Microbiological culture
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...

, and the researchers further reported having identified DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 in these structures by staining.

A paper published in 2000 by a team led by an NIH scientist John Cisar further tested these ideas. It stated that what had previously been described as "self-replication" was a form of crystalline
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...

 growth. The only DNA detected in his specimens was identified as coming from the bacteria Phyllobacterium mysinacearum, which is a common contaminant in PCR reactions.

Kajander and Ciftcioglu set up a company in Finland in 2000, Nanobac Oy, to market medical diagnostic kits for identifying nanobacteria to medical researchers, and develop prescription medical treatments for calcification-associated diseases. The company was absorbed in 2003 by Nanobac Pharmaceuticals, Inc., a publicly traded company in Tampa, Florida founded by nanobiotic developer Gary Mezo.

2001–present


In 2004 a Mayo Clinic
Mayo Clinic
Mayo Clinic is a not-for-profit medical practice and medical research group specializing in treating difficult patients . Patients are referred to Mayo Clinic from across the U.S. and the world, and it is known for innovative and effective treatments. Mayo Clinic is known for being at the top of...

 team led by Franklin Cockerill, John Lieske, and Virginia M. Miller, reported to have isolated nanobacteria from diseased human arteries
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....

 and kidney stone
Kidney stone
A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine...

s. Their results were published in 2004 and 2006 respectively. Similar findings were obtained in 2005 by László Puskás at the DNA Lab, University of Szeged, Hungary. Dr. Puskás identified these particles in cultures obtained from human atherosclerotic aortic walls and blood samples of atherosclerotic patients but the group was unable to detect DNA in these samples.

In 2005, Ciftcioglu and her research team at NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 used a rotating cell culture
Cell culture
Cell culture is the complex process by which cells are grown under controlled conditions. In practice, the term "cell culture" has come to refer to the culturing of cells derived from singlecellular eukaryotes, especially animal cells. However, there are also cultures of plants, fungi and microbes,...

 flask, which simulates some aspects of low-gravity conditions, to culture nanobacteria suspected of rapidly forming kidney stones in astronauts. In this environment, they were found to multiply five times faster than in normal Earth gravity. The study concluded that nanobacteria might have a potential role in forming kidney stones and may need to be screened for in crews pre-flight.

The February 2008 PLoS Pathogens article focused on the comprehensive characterization of nanobacteria. The authors say that their results rule out the existence of nanobacteria as living
Life
Life is a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not, either because such functions have ceased , or else because they lack such functions and are classified as inanimate...

 entities and that they are instead a unique self-propagating
Plant propagation
Plant propagation is the process of creating new plants from a variety of sources: seeds, cuttings, bulbs and other plant parts. Plant propagation can also refer to the artificial or natural dispersal of plants.-Sexual propagation :...

 entity, namely self-propagating mineral-fetuin
Fetuin
Fetuins are blood proteins that are made in the liver and secreted into the blood stream. They belong to a large group of binding proteins mediating the transport and availability of a wide variety of cargo substances in the blood stream. The best known representative of these carrier proteins is...

 complexes.

An April 2008 PNAS article also reported that blood nanobacteria are not living organisms and stated that "CaCO3 precipitates prepared in vitro are remarkably similar to purported nanobacteria in terms of their uniformly sized, membrane-delineated vesicular shapes, with cellular division-like formations and aggregations in the form of colonies." The growth of such "biomorphic" inorganic precipitates was studied in detail in a 2009 Science paper, which showed that unusual crystal growth mechanisms can produce witherite
Witherite
Witherite is a barium carbonate mineral, BaCO3, in the aragonite group. Witherite crystallizes in the orthorhombic system and virtually always is twinned. The mineral is colorless, milky white, grey, pale yellow, green, to pale brown. The specific gravity is 4.3, which is high for a translucent...

 precipitates from barium chloride and silica solutions that closely resemble primitive organisms. The authors commented on the close resemblance of these crystals to putative nanobacteria, stating that their results showed that evidence for life cannot rest on morphology alone.

See also

  • Mimivirus
    Mimivirus
    Mimivirus is a viral genus containing a single identified species named Acanthamoeba polyphaga mimivirus , or is a group of phylogenetically related large viruses . In colloquial speech, APMV is more commonly referred to as just “mimivirus”...

     — largest known virus
  • Mycoplasma genitalium
    Mycoplasma genitalium
    Mycoplasma genitalium is a small parasitic bacterium that lives on the ciliated epithelial cells of the primate genital and respiratory tracts. M. genitalium is the smallest known genome that can constitute a cell, and the second-smallest bacterium after the recently-discovered endosymbiont...

    , Pelagibacter ubique
    Pelagibacter ubique
    Pelagibacter, with the single species P. ubique, was isolated in 2002 and given a specific name, although it has not yet been validly published according to the bacteriological code. It is an abundant member of the SAR11 clade in the phylum Alphaproteobacteria...

    — some of the smallest known bacteria
  • Nanoarchaeum
    Nanoarchaeum
    Nanoarchaeum equitans is a species of tiny microbe, discovered in 2002 in a hydrothermal vent off the coast of Iceland by Karl Stetter. Since it grows in temperatures approaching boiling, it is considered to be a thermophile. Nanoarchaeum appears to be an obligatory symbiont on the archaeon...

    — smallest known archaeum
  • Protobiont
    Protobiont
    Protobionts are systems that are considered to have possibly been the precursors to prokaryotic cells. If RNA is trapped inside, the system can use the RNA or select for it....

    s — Aggregates of abiotically produced organic molecules, surrounded by a membrane
  • Nanobe
    Nanobe
    A nanobe is a tiny filamental structure first found in some rocks and sediments. Some scientists hypothesize that nanobes are the smallest form of life, 1/10 the size of the smallest known bacteria...

     — possible nano-organism first observed in 1996
  • Parvovirus
    Parvovirus
    Parvovirus, often truncated to "parvo", is both the common name in English casually applied to all the viruses in the Parvoviridae taxonomic family, and also the taxonomic name of the Parvovirus genus within the Parvoviridae family...

     — smallest known family of viruses
  • Prion
    Prion
    A prion is an infectious agent composed of protein in a misfolded form. This is in contrast to all other known infectious agents which must contain nucleic acids . The word prion, coined in 1982 by Stanley B. Prusiner, is a portmanteau derived from the words protein and infection...

    s — also controversial when first proposed in 1982
  • Ultramicrobacteria
    Ultramicrobacteria
    Ultramicrobacteria are bacteria that are considerably smaller than normal bacterial cells and are 0.3 to 0.2 micrometres in diameter. This term was first used in 1981, to refer to cocci in seawater that were less than 0.3 μm in diameter. These cells have also been recovered from soil and appeared...


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