📊 Transposon Analysis: Sequencing Depth Requirements

🔬 Purpose of Analysis

  • Tn-seq / TraDIS / INSeq
    Used for mapping transposon insertion sites across the genome.
    Recommended coverage: 500× to 1000×

  • Native transposon (IS) detection
    Detects existing mobile genetic elements such as insertion sequences (IS) or integrons.
    Recommended coverage: 30× to 50×

  • Structural variant (SV) or mobility analysis
    Identifies large insertions, deletions, or mobile element insertions.
    Recommended coverage: at least 50×

  • Abundance or fitness estimation
    Quantifies insertion events under different experimental conditions.
    Recommended coverage: 200× to 300×

  • Long-read mobile element assembly
    Uses technologies like Oxford Nanopore (ONT) or PacBio to resolve repetitive mobile elements.
    Recommended coverage: 20× to 30×


🧬 Your Data (Example Samples)

  • Sample 1
    Total bases: 2.0 Gbp
    Mean read length: 8,635 bp
    Estimated read count: ~233,000
    Approximate genome coverage: ~500×

  • Sample 2
    Total bases: 2.5 Gbp
    Mean read length: 6,851 bp
    Estimated read count: ~366,000
    Approximate genome coverage: ~625×

  • Sample 8
    Total bases: 1.26 Gbp
    Mean read length: 5,180 bp
    Estimated read count: ~243,000
    Approximate genome coverage: ~250×

  • Sample WT
    Total bases: 1.88 Gbp
    Mean read length: 10,910 bp
    Estimated read count: ~172,000
    Approximate genome coverage: ~600×

Assuming an average bacterial genome size of ~4 Mb


✅ Conclusion

  • Your sequencing depth ranges from 250× to 625×, which is:

    • Ideal for transposon insertion site mapping
    • Suitable for detecting low-abundance or rare insertion events
    • Adequate for native mobile element discovery
  • If your goal is Tn-seq, your current data provides excellent coverage for both insertion site resolution and abundance profiling.

📊 Recommended Sequencing Depths for Transposon Analysis

  • Tn-seq / TraDIS: Recommended depth is 500× to 1000×.
    This high depth is necessary to ensure adequate coverage across insertion sites and to detect low-frequency transposon insertions.

  • Detection of native insertion sequences (IS) / mobile elements: A depth of 30× to 50× is generally sufficient.
    This enables reliable identification of naturally occurring transposable elements in bacterial genomes.

  • Structural variants (SVs) and comparative genomics: Aim for more than 50× coverage.
    Higher coverage improves confidence in detecting large insertions, deletions, or rearrangements during comparative analysis.

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