|MadSci Network: Microbiology|
Chemolithotrophy is a biological process that we as humans often overlook, but whose impact on our lives and the environment should not be overlooked. These organisms are key in everyday processes such as nutrient cycling, and problems such as acid mine drainage. A good place to start here is the word. What does it mean? A good way to analyse science words is to break them down into their parts. CHEMO = chemical LITHO = rock TROPH = to eat. From this simple process we get the idea that chemolithotrophs are rock eaters. Not a perfect definition, but a good basic view of them. To be more precise they use inorganic compounds as energy sources (electron donors) for their catabolism (the biological process of making energy). You, as a human are a organotroph and use organic chemicals (sugars, fats, and proteins) such as glucose as an energy source. This process of using inorganic compounds generates less energy per molecule consumed. You also mention the idea of autotrophy. Again lets look at the words. AUTO = self TROPH = to eat. We use this term to mean organisms that can use carbon from non-organic forms for anabolism. Anabolism is the process of building new cellular material. Plants for example are autotrophs that can turn carbon dioxide into glucose. You, a human can not. Finally, how are these 2 interrelated and what types of organisms are they? If you live and have evolved to grown in an environment depleted of carbon for energy (catabolism) there would also be no carbon for new cell (anabolism). Therefore most of the organisms that are chemolithotrophs are also autotrophs, but not all. All of the organisms that do these reactions are single celled and most prokaryotes (bacteria and archaea). A good example for you to research would be Thiobacillus ferreoxidans. This causes acid mine drainage in many states and uses sulphur (thio) and iron (ferre) in its metabolism. I hope this helps you. Chemolithotrophs are extremely fun organisms that we still need to do a great deal of work on.
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