Auxotrophy

from Wikipedia, the free encyclopedia

When auxotrophic (Greek αυξανω "auxano" - "I grow" and τροφή "trophic" - "diet") refers to organisms that certain essential substances can not synthesize independently and thus are likely to tap these substances from the environment.

properties

An example of auxotrophy are lactic acid bacteria , which due to their specialization are dependent on nutrient-rich media and can no longer synthesize many vital substances themselves. If an organism is auxotrophic for a substance, this mutant is referred to as "Ade - " in the case of adenine auxotrophy, for example .

The opposite of auxotrophy is called prototrophy . These are organisms that are not dependent on supplines (growth factors), so they can synthesize all the necessary substances themselves.

Auxotrophies often occur as mutations in the genome as a result of mutagenesis . If you transform an auxotrophic mutant (colloquially: deficiency mutant ) with a vector that carries the missing functional gene, the intact gene can compensate for the auxotrophic defect. The mutant is then again able to synthesize the substance itself. In this case one speaks of a complementation .

If you transform an auxotrophic mutant with a vector that carries the complementing gene and a gene to be examined, you can check whether both genes have been successfully integrated into the organism, because the vector and thus the gene to be examined was only absorbed in the case of complemented mutants . Therefore, auxotrophic mutants are often used in modern genetics as an alternative to bacterial resistance markers when transforming genes.

If, in the case of many random mutants, deficiency mutants with respect to a substance never occur in an organism, it can be assumed that redundant biosynthetic pathways for this substance exist in this organism.

Auxotrophies are detected , among other things, by a growth inhibition test.

literature