Abiotic production

FIGURE 1-33 Abiotic production of biomolecules. Spark-discharge apparatus of the type used by Miller and Urey in experiments demonstrating abiotic formation of organic compounds under primitive atmospheric conditions. After subjection of the gaseous contents of the system to electrical sparks, products were collected by condensation. Biomolecules such as amino acids were among the products. 

The term biochemical stabilization refers to the biotic or abiotic production of organic substances that are refractory to decomposition by microorganisms and contribute, through condensation and complex formation, to the stabilization of otherwise easily decomposable substrates such as enzymes. This stabilization process coincides with the process of humification. 

In favour of the metabolism paradigm there are, first of all, the results of the simulation experiments, and in particular the fact that the abiotic production of amino acids is so much easier than that of nucleic acids. Chemistry tells us that the primitive Earth could indeed generate enormous amounts of organic molecules that were potentially capable of having some type of metabolism, and of producing structures as complex as Oparin s coacervates, Fox s microspheres, or Wachtershauser s vesicles. 

Nitric oxide and N2O are also produced abiotically by chemical decomposition of NO2 (Hooper and Terry, 1979). The reaction is favorable at low pH and yields mainly NO (van Cleemput and Baert, 1984), although N2O can also be produced (Martikainen and De Boer, 1993). Abiotic production of NO and N2O is assumed to be relatively unimportant in most ecosystems (e.g., Webster and Hopkins, 1996). 

Figure 5. Upper Abiotic production of 3-mercaptoproplonate (MP) and an unknown thiol ( ) in deaerated seawater from reaction of acrylic acid (0.1 mM) with sodium sulfide (1.0 mM) at 60°C for 2 hours under argon detection by fluorescence derlvatization and HPLC. Middle Control = sodium sulfide (1.0 mM) alone in seawater under identical reaction conditions as above. Lower Control = seawater alone under identical reaction conditions as above.

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