Astrobiology Workshop, Macquarie University July 12-13 2001

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Novel nano-organisms (Nanobes): living analogues for Martian "nannobacteria"?

Philippa J.R.Uwins (Centre for Microscopy and Microanalysis - The University of Queensland)

On August 7th 1996 NASA made the historic announcement that Martian Meteorite ALH84001 could contain evidence for past life on Mars. Central to the thesis, and perhaps the most controversial aspect of the findings, were the fossil remnants of sub-bacteria sized "cells" called nannobacteria. While the results were of great scientific interest they fuelled a fierce and highly contentious debate, not only concerning the existence of Martian microbes, but a controversy surrounding the minimum possible size of life on earth.

The identification and existence of nan(n)obacteria was not new and had been proposed previously by a number of workers. However, the likelihood of such small cells existing was strongly questioned, since it was argued that these cells would have been far too small to carry out the metabolic and reproductive processes essential for life. It has remained unresolved to this day whether these mineralised nannobacteria were fossilised remnants of independent life forms, artefacts of sample preparation or unusual mineral deposits.

However, more recently, we reported on the existence of novel nano-organisms (nanobes) growing on Triassic and Jurassic sandstones collected from petroleum exploration boreholes offshore Western Australia. These filamentous, pleomorphic and yeast-like cells provide further evidence for nano-scopic life in the same size range as the controversial Martian nannobacteria. Nanobes will be described, illustrated and discussed within the context of the nan(n)obacterial debate.