A cautionary note on the mutation frequency in microbial research

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Mutation frequency (MF) is historically dominant for measuring microbial mutability.
• MF is an unnormalized quantity, making it prone to variability and misinterpretation.
• Current methods using MF in mutator identification face significant challenges.

Purpose of the Study:

• To highlight the limitations of using mutation frequency in microbial research.
• To advocate for the adoption of mutation rates (MR) as a more robust metric.
• To draw attention to critical issues like false positive control and cell death.

Main Methods:

• Conceptual analysis and critique of existing methodologies in microbial mutability studies.
• Comparison of mutation frequency (unnormalized) versus mutation rate (normalized) metrics.
• Discussion of implications for experimental design and data interpretation.

Main Results:

• Mean mutation frequency is highly erratic and unreliable for assessing microbial mutability.
• Median mutation frequency does not effectively resolve the inherent issues of MF.
• Transitioning to mutation rates is essential for accurate and reproducible research.

Conclusions:

• Mutation rates provide a more accurate and reliable measure of microbial mutability than mutation frequencies.
• Adopting mutation rates will help address critical challenges in mutator identification, including false positives and nonmutant cell death.
• This shift is crucial for advancing the field of microbial genetics and experimental microbiology.