Structures found on meteorite fragment ALH84001

Nanobacteria (sometimes incorrectly called Nannobacteria ) are claimed to be cell walled microorganisms with a diameter well below the generally accepted lower limit (about 200 nanometres) for bacteria.

Claims of their being living organisms are controversial. If they are living, there is speculation that they may be a newly discovered form of life, rather than bacteria.

1996 Martian meteorite claims

Structures in the Martian meteorite ALH84001 have been interpreted by some as fossilized nanobacteria, but the origin of the structures is disputed.

1998-2000 claims

Nanobacterium sanguineum was proposed in 1998 as an explanation of certain kinds of pathologic calcification (apatite in kidney stones) by Finnish researcher Olavi Kajander and Turkish researcher Neva Ciftcioglu, working at the University of Kuopio in Finland. According to the researchers the particles self-replicated in microbiological culture, and claimed to have identified a DNA sequence.

Later studies by another group reached different results, suggesting peculiar yet inanimate etiology of the disease. A paper published in 2000 by a team lead by John Cisar of the US National Institutes of Health proposed that the "self-replication" was, in fact, an unusual form of crystaline growth, and that contamination may have been the source of the DNA. However, the Cisar group did not as part of their study examine nanobacteria samples from the Kajander group, therefore critics observed that without such a control sample the assertion that these were self-replicating crystals or contamination had not been substantiated.

The fact that the Finnish group set up a company in Finland "Nanobac Oy" later taken over by a company in Florida, 'Nanobac Life Sciences, Inc.', to sell kits for identifying nanobacteria, and are developing treatments for calcification-associated diseases, raised doubts concerning their impartiality. However such practices are commonplace among researchers throughout the U.S. and are generally accepted if transparently revealed, which in this case they were in filings submitted to the Securities and Exchange Commission.

April 2004 claims

In a press release Nanobac Life Sciences, Inc. claims that a strong correlation has been found between antibodies to nanobacteria and coronary artery calcification (associated with increased risk of coronary artery disease). The results were obtained using a testing kit produced by Nanobac and tests on 198 patients were led by Stephen Epstein , Director of the Cardiovascular Research Institute, Washington Hospital Center, Washington.

May 2004 claims

In 2004 a team lead by Dr. John Lieske of the Mayo Clinic in Minnesota claimed to have discovered nanobacteria in diseased human arteries. Their results were accepted by the American Journal of Physiology - Heart and Circulatory Physiology, Virginia M. Miller et al., in May 2004 after extensive revision.

Unlike the Finnish researchers, those at the Mayo Clinic apparently have no linked commercial interests. Working with particles less than 0.2 micrometres in size, they found indirect evidence that the particles had self-replicated, and found that they had a cell-like appearance under an electron microscope. They also believe that the particles are producing RNA, since they absorbed one of its building blocks, uridine, in greater quantities than would be expected in the case of pure absorption (by crystals such as apatite). Using an antibody produced by the Finnish researchers, the particles were found to bind to diseased arterial tissue, and to the same sites to which a DNA stain bound. The researchers now hope to isolate RNA and DNA from the particles.

February 2005 NASA Results

NASA announced the results of an experiment in which a bioreactor chamber that simulates conditions of space travel was used to culture nanobacteria suspected of rapidly forming kidney stones in astronauts. In this microgravity environment, they were found to multiply five times faster than in normal Earth gravity. NASA also determined that nanobacteria were shown to be a possible infectious risk for crew members living in close quarters.

See also

• Mycoplasma genitalium, Pelagibacter ubique - some of the smallest known bacteria
• Nanoarchaeum - smallest known archaeum
• Parvovirus - smallest known family of viruses
• Prions - also controversial when first proposed in 1982
• Nanobe - nano-organism first observed in 1996

External links

• Nanobacteria: An alternative mechanism for pathogenic intra- and extracellular calcification and stone formation
• An alternative interpretation of nanobacteria-induced biomineralization
• Claim made for new form of life, BBC News, May 19, 2004
• New Scientist article about nanobacteria
• Evidence of Nanobacterial-like Structures in Human Calcified Arteries and Cardiac Valves
• Nanobac press release, April 2004
• Abstract: American Journal Physiology - Heart and Circulatory Physiology May 13, 2004
• Infectious Microorganism Linked to Kidney Stones and other Diseases, February 2005
• Are Nanobacteria Making Us Ill?, Wired News, Mar. 14, 2005
• The Calcium Bomb - The Nanobacteria Link to Heart Disease and Cancer
• Nanobacteria Theory Disproven by Elmer M. Cranton, M.D.