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#prototroph

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Microbial genetics

An organism that can synthesize all essential metabolites is called

In microbial genetics Beadle and Tatum defined prototroph as wild-type strain capable of growth on minimal medium containing only inorganic salts, carbon source, and biotin requirements, because its genome encodes complete biosynthetic pathways for all essential metabolites like amino acids, vitamins, purines. Prototrophs synthesize compounds de novo from simple precursors. They represent parental wild-type phenotype against which auxotrophic mutants blocked in specific pathways are scored. Prototroph selection on minimal plates underpins genetic mapping of mutations, recombination analysis, and complementation tests in bacteria and Neurospora.

Ref: Griffiths et al., Introduction to Genetic Analysis, 12th ed., Chapter 6: Microbial Genetics – Prototrophy

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Gene Dissection and Complementation

An organism that can synthesize all required growth factors is called

Prototrophy denotes wild-type metabolic autonomy where organism synthesises all essential metabolites from inorganic precursors, enabling growth on minimal medium lacking amino acids or vitamins. Such strains carry functional alleles for entire biosynthetic network including enzymes for amino acid, nucleotide and cofactor synthesis. Auxotrophs carry loss-of-function mutation in one enzyme and require exogenous supply of specific end product for growth. Neurospora wild type and Escherichia coli K12 serve as classic prototrophs used as reference for mutant selection, transformation and mapping experiments in microbial genetics research.

Ref: Pierce, Genetics: A Conceptual Approach, 7th ed., Chapter 16: Prototrophs Auxotrophs Minimal Medium Concept

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