In 1898 Martinus Beijerinck coined the term contagium vivum fluidum “contagious living fluid” to describe the cause of a disease. Beyond revolutionary, the idea that there were entities smaller than bacteria which could cause disease was almost heretical at the time. Of course, Beijerinck was referring to viruses, as we subsequently found out. The next paradigm shift in our understanding of infectious agents came in 1982, when Stanley Prusiner proposed the concept of the prion, infectious self-reproducing pathogens solely composed of protein (Novel proteinaceous infectious particles cause scrapie. 1982 Science 216: 136-144). And in 1998, Olavi Kajander proposed the name nanobacteria for objects claimed to be the smallest cell-walled bacteria, dwarfed by the tiniest living cell and smaller than many viruses (Nanobacteria: An alternative mechanism for pathogenic intra- and extracellular calcification and stone formation. 1998 PNAS USA 95: 8274-8279).
Nanobacteria are said to have a hard mineral shell, replicate like a living organism and are wiped out by antibiotics and radiation, yet seem to lack DNA. This proposal was controversial to say the least, and has been described as “the cold fusion of microbiology”. So, are “nanobacteria” fact or fiction? A recent article in PLoS Pathogens takes a highly skeptical view (Nanobacteria: Facts or Fancies? 2007 PLoS Pathogens 3, 5, e55).
Nanobacteria have been claimed to be present in animal and human blood and other body fluids, in tissue culture cell lines, wastewater, rocks, in the stratosphere and in meteorites from Mars (Nanobacteria-like calcite single crystals at the surface of the Tataouine meteorite. 2003 PNAS USA 100: 7438-7442). Most of the reports are based on the visualization of nanobacteria by electron microscopy, but Kajander and his colleagues claim they can be propagated in cell-free tissue culture media (unlike viruses, which are obligate parasites requiring host cells for replication).
What seems clear is that nanobacteria are efficient nuclei of mineralization which start the formation of apatite crystalline structures from soluble calcium and phosphorus compounds at physiologic concentrations and conditions, such as in tissue culture medium. Following Kajander’s lead other authors have reported nanobacteria in association with a variety of pathological calcifications, such as kidney stones (nephrolithiasis), gallstones (cholecystolithiasis), vascular plaques, ovarian and breast cancer and many others.
Nanobacteria are said to be minute bodies ranging in size from 20 to 500 nm, the smaller ones filterable through membranes with 100 nm pores. They are highly variable in appearance, appearing as spheres or rods. The only constant factor seems to be their coat of apatite, which is formed from soluble calcium and phosphorus compounds in their environment or medium. Unfortunately, experienced microbiologists who failed to reproduce the ability of Kajander and his colleagues to grow nanobacteria in cell culture media such as Dulbecco minimal essential medium or RPMI-1640 (Attempted isolation of Nanobacterium sp. microorganisms from upper urinary tract stones. 2003 J Clin Microbiol 41: 368-372) received a rambling and insubstantial response from the original authors (Pitfalls in detection of novel nanoorganisms. J Clin Microbiol 41: 3460-3461).
The data which is claimed to demonstrate that nanobacteria contain DNA, synthesize proteins and at least one antigen, and incorporate uridine at very low levels barely above that of negative controls, is thin to say the least (Evidence of nanobacterial-like structures in calcified human arteries and cardiac valves. 2004 Am J Physiol Heart Circ Physiol 287: H1115-H1124). Kajander himself recently admitted that the bacterial status of nanobacteria is still lacking satisfactory evidence, and conceded that the term “calcifying nanoparticles” might better describe these agents (Nanobacteria – Propagating calcifying nanoparticles. 2006 Lett Appl Microbiol 42: 549-552).
What’s the difference between nanobacteria and UFOs? You can’t get abducted by nanobacteria. So there we have it: nanobacteria – honest mistake or complete tosh? Decide for yourself.
Except that you don’t have to do that. For generations, science has advanced based on a process called peer review, in which an author’s work or ideas are subjected to the scrutiny of others who are experts in the field. They spot the obvious flaws and pitfalls it’s all too easy to overlook when you’ve spent a long time working on a particular idea. And then the general public, or those who are interested, get to read the final published version. But now, running scared of the loss of revenue they face from Open Access journals, Nature Publishing has come up with Nature Preceedings, taking upon itself removal of the peer review process from scientific publishing (which still applies to Open Access journals such as PLoS). What if Kajander had “published” his original paper on “nanobacteria” in Nature Preceedings? How much public money (which could be spent on preventing or curing AIDS, malaria or tuberculosis) would have been wasted? Or would the route of publication not have made any difference? What do you think? Leave a comment below.