The key difference between chemoorganotrophs and chemolithotrophs is that chemoorganotrophs are organisms that obtain electrons from organic compounds, while chemolithotrophs are organisms that obtain electrons from inorganic compounds.
Living organisms can be grouped into several categories in relation to the nutritional mode based on the source of energy and carbon. There are sources of energy as sunlight and organic compounds. Similarly, there are two types of sources of carbon as inorganic carbon and organic carbon. The four main categories are photoautotrophs, photoheterotrophs, chemoautotrophs and chemoheterotrophs. Moreover, based on the primary source of reducing equivalent, there are two categories as organotrophs and lithotrophs. Chemoorganotrophs and chemolithotrophs are two groups that use energy from breaking chemical compounds. But, they differ from each other based on the electron donor. The source of electron donor is organic compounds in chemoorganotrophs while the source of reducing equivalent is inorganic in chemolithotrophs.
CONTENTS
1. Overview and Key Difference
2. What are Chemoorganotrophs
3. What are Chemolithotrophs
4. Similarities Between Chemoorganotrophs and Chemolithotrophs
5. Side by Side Comparison – Chemoorganotrophs vs Chemolithotrophs in Tabular Form
6. Summary
What are Chemoorganotrophs?
Chemoorganotrophs are organisms that obtain energy from breaking chemical compounds and electrons from organic compounds. Therefore, their source of reducing equivalents is the organic compound. In simple words, chemoorganotrophs use organic compounds as their electron donors. Therefore, they totally depend on organic chemicals for their energy and carbon. Generally, they oxidize chemical bonds of organic compounds such as sugars (i.e. glucose), fats and proteins as their energy source.
Figure 01: Chemoorganotroph
Predatory, parasitic, and saprophytic prokaryotes, some eukaryotes, such as heterotrophic protists, and animals are chemoorganotrophs. Moreover, some archaea are chemoorganotrophs. Moreover, fungi are also chemoorganotrophic due to their use of organic carbon as both an electron donor and a carbon source.
What are Chemolithotrophs?
Chemolithotrophs are organisms that depend on inorganic reduced compounds as a source of energy. Chemoautotroph is a synonym of chemolithotroph. Only some prokaryotes show this mode of nutrition, especially some bacteria and Archaea. Common chemolithotrophs are methanogens, halophiles, sulfur oxidizers and reducers, nitrifiers, anammox bacteria, and thermoacidophiles.
Figure 02: Chemolithotroph
Chemolithotrophs are exclusively microorganisms. H2S, S0, S2O32−, H2, Fe2+, NO2−or NH3 are several inorganic electron donors that are involving in chemolithotrophy. These organisms oxidize electron donors in their cells and send electrons to respiratory chains in order to produce ATP. Therefore, electron acceptors can be oxygen or organic or inorganic species. Based on that, chemolithotrophs can be lithoautotrophs or lithoheretotrophs.
What are the Similarities Between Chemoorganotrophs and Chemolithotrophs?
- Both chemoorganotrophs and chemolithotrophs are chemotrophs that obtain energy by the oxidation of electron donors in their environments.
- They belong to two main categories of organisms in relation to the nutrition mode.
What is the Difference Between Chemoorganotrophs and Chemolithotrophs?
Chemoorganotrophs are organisms that obtain energy by the oxidation of organic compounds. In contrast, chemolithotrophs are microorganisms that obtain energy by the oxidation of inorganic compounds. So, this is the key difference between chemoorganotrophs and chemolithotrophs.
Moreover, chemoorganotrophs mainly utilize sugars (especially glucose), fats and proteins as their electron donors while chemolithotrophs utilize H2S, S0, S2O32−, H2, Fe2+, NO2− or NH3 etc as their electron donors. Therefore, we can consider this also a difference between chemoorganotrophs and chemolithotrophs.
Summary – Chemoorganotrophs vs Chemolithotrophs
Chemotrophs utilize energy by oxidizing sources of electron donors in their surroundings. Based on the reducing compound, there are two types of chemotrophs as chemoorganotroph and chemolithotroph. If the electron donor material is organic, the organism is said to be chemoorganotroph; if the electron donor material is inorganic, the organism is said to be chemolithotroph or chemoautotroph. So, this is the key difference between chemoorganotrophs and chemolithotrophs. In addition to that, chemolithotrophs are exclusively microbes while chemoorganotrophs include some eukaryotic organisms.
Reference:
1. “Chemolithotrophy.” Lumen, Available here.
2. “Primary Nutritional Groups.” Wikipedia, Wikimedia Foundation, 23 May 2019, Available here.
Image Courtesy:
1. “K 1033CR08-9 Yellow fungus on stalk” (CC BY-SA 3.0) via Commons Wikimedia
2. “Gallionella ferruginea in Korrosionsprodukt” By Koelle (CC BY-SA 3.0) via Commons Wikimedia