The key difference between auxotrophs and prototrophs is that auxotrophs are mutant microorganisms that have lost the ability to produce a particular organic compound required for their growth while prototrophs are wild type microorganisms that are capable of producing all required organic compounds.
Microorganisms show different modes of nutrition. Particularly, bacteria have different abilities. Some bacteria are capable of photosynthesizing and producing their own food while some bacteria live in symbiotic relationships with their host organism and obtain nutrients. Furthermore, some bacteria degrade organic matter and acquire nutrients. Auxotrophs and prototrophs are two groups of microorganisms that differ based on their ability to produce organic compounds for their growth. Prototrophs can synthesize all organic compounds required for their growth while autotrophs are unable to produce a particular organic compound which is essential for its growth due to a mutation.
CONTENTS
1. Overview and Key Difference
2. What are Auxotrophs
3. What are Prototrophs
4. Similarities Between Auxotrophs and Prototrophs
5. Side by Side Comparison – Auxotrophs vs Prototrophs in Tabular Form
6. Summary
What are Auxotrophs?
Auxotrophs are mutant organisms, especially mutant microorganisms. They have lost their ability to produce a particular organic compound such as an amino acid, nucleotide, vitamin, etc., which is vital for their growth. A mutation is responsible for the loss of this ability. Therefore, these organisms are unable to produce certain organic compounds, unlike prototrophs or their wild type strains. Therefore, when growing auxotrophs in culture media, it is necessary to provide a specific growth substance beyond the minimum required for normal metabolism and reproduction in comparison to the wild type strain of them.
Figure 01: Auxotrophy
The term “auxotrophy” is specifically used in relation to a particular compound. For example, methionine auxotroph refers to an organism that cannot synthesize methionine due to a mutation. Furthermore, in genetics, auxotrophic refers to an organism that carries a mutation causing the inability to synthesize an essential compound. For instance, yeast mutant with an inability to synthesize uracil is a uracil auxotroph.
In molecular genetics, auxotrophs are popular genetic markers that facilitate mapping of biosynthetic or biochemical pathways of mutated and dysfunctional enzymes, etc. Moreover, auxotrophy is important in genetic analysis of microorganisms.
What are Prototrophs?
Prototrophs are the organisms that have the ability to synthesize all organic compounds required for growth. Therefore, they are self-sufficient. In fact, they are similar to the wild type strains that do not have mutations. Hence, they are non-mutants and have similar nutritional requirements of the wild type. These microorganisms synthesize their nutrients from inorganic materials. Therefore, they do not need organic nutrients from the outside. They grow well in minimal media or media that lack supplements. Most importantly, they can grow in a medium that contains only simple carbohydrate such as a sugar as a source of energy, CO2 carbon source and water. They synthesize all they need from inorganic salts.
What are the Similarities Between Auxotrophs and Prototrophs?
- Auxotrophy and prototrophy are two contrasting terms.
- There are auxotrophic bacteria as well as prototrophic bacteria.
- Both types are useful markers for genetic analysis.
- Also, they are alternative phenotypes that are often determined by a pair of alleles.
- Moreover, both can be studied genetically to find out their resistance and sensitivity to an inhibitor.
What is the Difference Between Auxotrophs and Prototrophs?
Auxotrophs and prototrophs are alternative phenotypes. Auxotrophs are organisms that are unable to produce a particular organic compound required for their growth while prototrophs are organisms that can synthesize all organic compounds required for their growth from inorganic compounds. So, this is the key difference between auxotrophs and prototrophs. Moreover, auxotrophs are mutant strains, while prototrophs are similar to wild type strains. Therefore, this is also a difference between auxotrophs and prototrophs.
The below infographic summarizes the difference between auxotrophs and prototrophs.
Summary – Auxotrophs vs Prototrophs
Auxotrophy is the inability of an organism to synthesize a particular organic compound required for its growth while prototrophy is the ability of an organism to synthesize all the compounds needed for its growth. Therefore, auxotrophs are unable to produce a particular organic compound needed for their growth while prototroph can synthesize all required compounds. So, this is the key difference between auxotrophs and prototrophs. Auxotrophs have lost their ability due to a mutation. Therefore, they are mutant strains that show an additional nutrient requirement. Meanwhile, prototrophs do not have mutations, and they are self-sufficient. Hence, they are wild type strains. Thus, this is the summary of the difference between auxotrophs and prototrophs.
Reference:
1. “Auxotrophy.” Wikipedia, Wikimedia Foundation, 2 Aug. 2019, Available here.
2. Griffiths, Anthony JF. “Working with Microorganisms.” Modern Genetic Analysis., U.S. National Library of Medicine, 1 Jan. 1999, Available here.
Image Courtesy:
1. “AUXOTROPHY Fig 1Replica plating growth comparison between Arg- Auxotroph and Prototroph” By Akardoust – Own work (CC BY-SA 4.0) via Commons Wikimedia