Not to Be?

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Science  03 Nov 2000:
Vol. 290, Issue 5493, pp. 901-903
DOI: 10.1126/science.290.5493.901e

Geologists have observed 0.1 micrometer coccoid particles (thought to reflect the presence of very small microorganisms, or “nanobacteria”) in minerals and meteorites, and biologists have implicated nanobacteria as nucleators in the formation of kidney stones. These findings and that of biomineralization in culture medium have been taken as a hallmark of the presence of nanobacteria; calcified particles from 0.45 μm filtrates of biological samples have been found to contain DNA and to support the transfer of biomineralization activity.

Cisar et al. have re-examined the evidence for nanobacteria, but they have failed to find nucleic acid or protein in decalcified samples, although they still observed transferable biomineralization activity. In addition, a closer look at the 16S rDNA sequences previously ascribed to nanobacterial species showed they were virtually identical to those of a notorious contaminating organism, Phyllobacterium mysinacearum. The transferable biomineralization activity appeared to be microcrystalline apatite (a constituent of teeth and bone) in combination with macromolecular triggers, such as phospholipids. Thus, it seems neither this world nor any other are yet ready for nanobacteria. — CA

Proc. Natl. Acad. Sci.U.S.A.97, 11511 (2000).

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