Related Experiment Video
Updated: Aug 12, 2026
Transformation of Probiotic Yeast and Their Recovery from Gastrointestinal Immune Tissues Following Oral Gavage in Mice
Published on: February 8, 2016
Induction and isolation of mutants in fungi at low mutagen doses
1Department of Genetics, Agricultural University, Wageningen, The Netherlands.
Abstract:
Since the yield of mutants per surviving cell increases in general with increasing dose of mutagen, it has often been concluded in the literature that it is the most efficient to apply high mutagen doses so that most spores are killed. As high doses of mutagen produce chromosome rearrangements and unnoticed mutations which disturb the genetic background, the relationship between mutant frequency and survival was analyzed with Aspergillus nidulans as a model. It is shown that for different types of mutants the highest mutant yield is obtained at low mutagen doses (20-50% survival). Mutant frequency increases with increasing dose of mutagen but levels off and even decreases at higher dosages. There is no simple linear relationship between mutant frequency and the logarithm of the mutagen dose or the logarithm of the surviving fraction. If appropriate enrichment procedures are also available auxotrophic mutants can best be isolated at low doses of mutagen. Taking into account the disturbance of the genetic background, mutation induction should be done preferentially at a survival level of at least 70%.
Insights
High mutagen doses are not optimal for mutant yield. Research shows that lower mutagen doses (20-50% survival) yield more mutants and minimize genetic background disturbance in Aspergillus nidulans.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Previous studies suggested high mutagen doses maximize mutant yield by reducing survival rates.
- High mutagen doses can lead to detrimental chromosome rearrangements and mutations, disrupting the genetic background.
Purpose of the Study:
- To analyze the relationship between mutant frequency and survival rates using Aspergillus nidulans as a model organism.
- To determine optimal mutagen doses for maximizing mutant yield while minimizing genetic instability.
Main Methods:
- Experimental analysis of mutant frequency and survival rates across varying mutagen doses.
- Utilizing Aspergillus nidulans as a model for mutation induction studies.
Main Results:
- The highest mutant yield was observed at low mutagen doses, corresponding to 20-50% survival.
- Mutant frequency initially increases with mutagen dose but plateaus or decreases at higher doses.
- No simple linear correlation exists between mutant frequency and the logarithm of mutagen dose or surviving fraction.
Conclusions:
- Optimal mutant yield is achieved at low mutagen doses, not high doses that kill most cells.
- Mutation induction is preferably performed at a survival level of at least 70% to avoid genetic background disturbances.
- Low mutagen doses are recommended for isolating auxotrophic mutants, especially with enrichment procedures.
