Genomic instability and biofilm determinants in Streptococcus mutans: insights from a sequence-defined arrayed
Ana Karen Solano Morales1,2, Emanuel Cazano1, Cara Pirani1
1Department of Biological Sciences, Beck College of Sciences and Mathematics, Arkansas State University, Jonesboro, Arkansas, USA.
Biorxiv : the Preprint Server for Biology
|April 3, 2026
Summary
This study created a new mutant library for Streptococcus mutans to identify biofilm genes. It found genomic instability in mutants, emphasizing the need for whole-genome verification in functional genomics.
Area of Science:
- Microbiology
- Genomics
- Dental Research
Background:
- Streptococcus mutans causes dental caries by forming resilient biofilms.
- Pooled genetic screens miss some gene functions due to community masking.
- A sequence-defined mutant library is needed to study individual gene contributions to biofilms.
Purpose of the Study:
- To create and utilize a comprehensive arrayed mutant library of Streptococcus mutans.
- To identify novel genes involved in biofilm formation.
- To assess genomic stability within the mutant library and its impact on functional genomics.
Main Methods:
- Construction of an arrayed mutant library of 9,216 Streptococcus mutans mutants.
- Application of Cartesian Pooling-Coordinate Sequencing (CP-CSeq) for sequence definition.
- Screening of individual mutants and whole-genome sequencing (WGS) for verification.
Main Results:
- Identification of novel biofilm determinants, including SMU_635 and SMU_2160.
- Discovery of significant genomic instability, with 25% recombination at gtfBC and 7% Tn Smu1 loss.
- Demonstration that gtfBC deletions, not Tn Smu1 loss, caused severe biofilm defects.
Conclusions:
- A sequence-defined arrayed mutant library is a powerful resource for Streptococcus mutans research.
- Genomic instability can lead to misattribution of gene function in functional genomics studies.
- Systematic whole-genome verification is essential for accurate genetic analysis and target identification.
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