Publication

Book	Encyclopedia of Geobiology
Editor	, Joachim Reitner & Volker Thiel
Publisher	Springer Science+Business Media, New York City
Page(s)	677 - 680
ISBN	10.1007/978-1-4020-9212-1_154
Title of proceedings	Encyclopedia of Geobiology

The term “nan(n)obacteria” has been originally proposed by Folk (1993) to describe 20–200 nm wide nanovesicles observed in carbonates using scanning electron microscopy (SEM). Kajander and Çiftçioglu (1998) defined the role of similar tiny particles in kidney stone formation. Based on their mineralogical properties, nan(n)obacteria have also been called calcifying nanoparticles (CNP) by these authors. Nan(n)obacteria-like particles have been observed in Martian meteorites, thereby raising questions about a primitive form of life (Bradley et al., 1997). CNP are studied extensively in pathogenic diseases as infectious agents by nucleating crystals (hydroxyapatite). Therefore, some comparisons have tentatively been made with the geological record. Although they display some evidences of bacterial nature, their living status is subject to controversy because of their small size and the fact that DNA extraction remains unsuccessful. On one hand, biologists discuss their metabolic existence and on the other hand geologists argue for widespread organic fossilization in palaeoenvironments. When interrelations between geology and microbiology are possible, they are looked at only from the point of view of experimental procedures (e.g., one emphasizes the use of DNA probes in geological samples). This prohibits an objective comparison of these very small particles.