Bacterial fossils

When considering how the evolution of life could have come about, the seeding of terrestrial life by extraterrestrial bacterial spores traveling through space (panspermia) deserves mention. Much is said about the possibility of some form of life on other planets, including Mars or more distant celestial bodies. Is it possible for some remnants of bacterial life, enclosed in a protective coat of rock dust, to have traveled enormous distances, staying dormant at the extremely low temperature of space and even surviving deadly radiation The spore may be neither alive nor completely dead, and even after billions of years it could have an infinitesimal chance to reach a planet where liquid water could restart its life. Is this science fiction or a real possibility We don t know. Around the turn of the twentieth century Svante Arrhenius (Nobel Prize in chemistry 1903) developed this theory in more detail. There was much recent excitement about claimed fossil bacterial remains in a Martian meteorite recovered from Antarctica (not since... 

Petersen, N. von Dobeneck,T. Vali, H. (1986) Fossil bacterial magnetite in deep-sea sediments from the South Atlantic Ocean. Nature 320 611-615... 

Aliphatic hydrocarbons such as n-alkanes and n-alkenes have been successfully used to distinguish between algal, bacterial, and terrestrial sources of carbon in estuarine/coastal systems, and also anthropogenic fossil sources (e.g., petroleum hydrocarbons). 

Doolittle WF (1998) You are what you eat a gene transfer ratchet could account for bacterial genes in eukaryotic nuclear genomes. Trends Genet 14 307-311 Doolittle WF (1999) Phylogenetic classification and the universal tree. Science 284 2124-2129 Douzery EJ, Snell EA, Bapteste E, Delsuc F, Philippe H (2004) The timing of eukaryotic evolution does a relaxed molecular clock reconcile proteins and fossils Proc Natl Acad Sci USA 101 15386-15391... 

Fig. 3. Gradient (4-20%) acrylamide gel of bone extracts from a fossil whale bone (10,000 years b.p.). Soluble extract (A) shows a range of molecular weights that are stained with Coomassie Brilliant Blue. The insoluble (in guanidine/EDTA) extract was heated in gel sample buffer at 100° for 30 min, and the buffer was removed. This insoluble extract also has a range of molecular weights that tend to be higher on average than the EDTA-soluble component. The soluble extract was digested with bacterial collagenase (B), and two products with molecular weights similar to albumin and osteonectin were revealed.

In conclusion, such a model is convenient to get an idea of the calcium oxalate concentration, CO2 pressure and conditions for potential precipitation of secondary calcium carbonate through oxalotrophic bacterial activity. It demonstrates that as long as calcium is available and oxalotrophic bacteria are present, transformation of oxalate into carbonate can occur under normal conditions found in soils and surficial sediments. Therefore, an oxalate-carbonate cycle, or at least pathway, must exist at the surface of continents (Verrecchia Dumont, 1996), explaining the absence of calcium oxalate accumulation in soils and the fossil record. 

The presence of organic impurities in fossil as well as in the HCl-soluble fraction of modem bone collagen indicates that part of these non-collagen organics may be a component of bone, possibly carbohydrates. It is possible that upon fossilization under certain environmental conditions of burial, the relative amount of these materials increases independently of age. This may result from bacterial reworking of the bone organic matter. 

Rohmer, M. (2008) From molecular fossils of bacterial hopanoids to the formation of isoprene units discovery and elucidation of the methylerythritol phosphate pathway. Lipids, 43,1095-107. 

---