Auxotroph – Definition & Meaning

The term “auxotroph” might not be a common word in everyday language, but it has significant importance in the field of biology. It is a term used to describe a type of organism that has a specific nutritional requirement that it cannot synthesize on its own. This article aims to provide an in-depth understanding of the definition, origin, and meaning of auxotroph.


Auxotroph is a term used to describe a type of organism that requires a specific nutrient that it cannot produce on its own. This nutrient is essential for the organism’s growth and survival. Without this nutrient, the organism cannot grow or reproduce.


The term auxotroph was first introduced in the early 1940s by Edward Tatum and George Beadle, who were studying the genetics of the bread mold, Neurospora crassa. They discovered that certain strains of this mold required specific nutrients that other strains could produce on their own. They named these strains “auxotrophs.”

Meaning in different dictionaries

According to the Oxford English Dictionary, auxotroph is defined as “an organism that requires a specific nutrient that it cannot synthesize on its own.” Merriam-Webster defines it as “a mutant strain of a microorganism that requires a particular nutrient that is absent from the diet of the parent strain.” The Cambridge Dictionary defines it as “a type of organism that needs a particular nutrient in order to grow.”


Auxotroph is a term commonly used in the field of microbiology and genetics. It is often used to describe the nutritional requirements of microorganisms and how they can be manipulated to study genetic mutations and metabolic pathways.


Some synonyms of auxotroph include:

  • Nutrient-dependent.
  • Nutrient-requiring.
  • Nutrient-sensitive.
  • Nutritionally deficient.


The antonym of auxotroph is prototroph. A prototroph is an organism that can synthesize all the nutrients it needs for growth and survival.

The same root words

The word auxotroph is derived from the Greek words “auxein,” meaning “to increase,” and “trophe,” meaning “nourishment.” Other words derived from these roots include:

  • Auxin: a plant hormone that promotes growth.
  • Trophic: relating to nutrition or growth.
  • Atrophy: the wasting away or degeneration of tissues or organs due to lack of nutrition or use.

Example Sentences

  • The auxotroph bacteria were unable to grow in the absence of the specific nutrient.
  • The study aimed to identify the genetic mutations that caused the auxotroph phenotype in the microorganisms.
  • The researchers used auxotroph mutants to study the metabolic pathways of the microorganisms.
  • The auxotroph strains of the bread mold were unable to grow on a nutrient-poor medium.
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