2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 5
Presentation Time: 2:35 PM


KIRKLAND, Brenda L.1, LYNCH, F. Leo1, CULPEPPER, Jonathan D.1, FRATESI, Sarah E.1, KUKLINSKI, Richard F.2, LAWRENCE, Amanda2 and MONROE, William A.2, (1)Dept. of Geosciences, Mississippi State University, Mississippi State, MS 39762, (2)Electron Microscope Center, Mississippi State University, Mississippi State, MS 39762, claynac@ra.msstate.edu

As in the case of Bigfoot and the Loch Ness monster, conclusive evidence for the existence of nannobacteria is rare and often promoted by kooks. Because of their small size and elusive nature, investigation of nannobacteria challenges standard petrographic and biologic techniques. Nevertheless it is clear that in most, if not all, cases a strong relationship exists between nanometer-scale textures, organic matter, and mineral precipitation.

Biological staining of sections of paraffin-impregnated samples from Italian hot springs reveals organic material at the nucleation sites of aragonite splays. In SEM nannobacteria are abundant in the stained zones. In other environments similar nannobacteria-centered botryoidal splays are formed by iron oxides and opal.

Standard SEM preparation techniques can destroy and distort the morphology of organic biofilms and bacteria in rocks, in some cases completely removing the organic mucilage, and in others leaving components that closely resemble purported nannobacteria. Nevertheless, gently and minimally dehydrated samples, especially those from hot springs, clearly show nannobacteria. Samples from one Italian hot spring, when examined using TEM, reveal abundant bacteria as well as intriguing nanometer-scale circular sections that may be nannobacteria.

Careful sample preparation and analysis repeatedly presents strong evidence for the existence of nannobacteria. Absolute evidence that these small, spherical structures are living organisms remains elusive. However, the intimate relationship clearly shown between organic material and mineral formation is inescapable and forces us to reconsider the boundary between organic and inorganic in geology.