quast

Tags: assembly quality assessment metrics bactopia-tool

Quality assessment of assembled contigs using QUAST.

This Bactopia Tool uses QUAST to evaluate the quality of assembled contigs. QUAST (Quality Assessment Tool for Genome Assemblies) generates comprehensive reports including numerous plots and tables that help assess assembly quality metrics such as N50, GC content, genome fraction, and misassembly rates. It produces both per-sample assessments and merged summaries for comparative analysis across multiple samples.

Usage

Bactopia CLI:

bactopia --wf quast \
  --bactopia /path/to/your/bactopia/results

Nextflow:

nextflow run bactopia/bactopia/workflows/bactopia-tools/quast/main.nf \
  --bactopia /path/to/your/bactopia/results

Outputs

Expected Output Files

<BACTOPIA_DIR>
├── <SAMPLE_NAME>
│   └── tools
│       └── quast-<TIMESTAMP>
│           ├── <SAMPLE_NAME>.tsv
│           ├── logs
│           │   ├── nf.command.{begin,err,log,out,run,sh,trace}
│           │   ├── quast.log
│           │   └── versions.yml
│           └── supplemental
│               ├── basic_stats
│               │   ├── <SAMPLE_NAME>_GC_content_plot.pdf
│               │   ├── GC_content_plot.pdf
│               │   ├── NGx_plot.pdf
│               │   ├── Nx_plot.pdf
│               │   └── cumulative_plot.pdf
│               ├── icarus.html
│               ├── icarus_viewers
│               │   └── contig_size_viewer.html
│               ├── predicted_genes
│               │   ├── <SAMPLE_NAME>_glimmer.stderr
│               │   └── <SAMPLE_NAME>_glimmer_genes.gff
│               ├── report.html
│               ├── report.pdf
│               ├── report.tex
│               ├── report.tsv
│               ├── report.txt
│               ├── transposed_report.tex
│               └── transposed_report.txt
└── bactopia-runs
    └── quast-<TIMESTAMP>
        ├── merged-results
        │   ├── logs
        │   │   └── quast-concat
        │   │       ├── nf.command.{begin,err,log,out,run,sh,trace}
        │   │       └── versions.yml
        │   └── quast.tsv
        └── nf-reports
            ├── quast-dag.dot
            ├── quast-report.html
            └── quast-timeline.html

Per-Sample Results

File	Description
*.tsv	Summary statistics of QUAST assessment for each sample
basic_stats/	Directory containing plots of assembly metrics (GC content, NGx, Nx)
icarus.html	Icarus main menu with links to interactive viewers
icarus_viewers/	Additional reports and viewers for Icarus
predicted_genes/	Directory containing predicted gene information
report.*	Assessment summary in various formats (html, pdf, tex, tsv, txt)
transposed_report.*	Transposed version of the assessment summary (tex, tsv, txt)

Merged Results

File	Description
quast.tsv	Merged TSV file with QUAST summary statistics from all samples

Audit Trail

Below are files that can assist you in understanding which parameters and program versions were used.

Logs

Each process that is executed will have a folder named logs. In this folder are helpful files for you to review if the need ever arises.

Extension	Description
.begin	An empty file used to designate the process started
.err	Contains STDERR outputs from the process
.log	Contains both STDERR and STDOUT outputs from the process
.out	Contains STDOUT outputs from the process
.run	The script Nextflow uses to stage/unstage files and queue processes based on given profile
.sh	The script executed by bash for the process
.trace	The Nextflow trace report for the process
versions.yml	A YAML formatted file with program versions

Nextflow Reports

These Nextflow reports provide great a great summary of your run. These can be used to optimize resource usage and estimate expected costs if using cloud platforms.

Filename	Description
quast-dag.dot	The Nextflow DAG visualization
quast-report.html	The Nextflow Execution Report
quast-timeline.html	The Nextflow Timeline Report
quast-trace.txt	The Nextflow Trace report

Parameters

Required Parameters

Define where the pipeline should find input data and save output data.

Parameter	Type	Default	Description
--bactopia	string		The path to bactopia results to use as inputs

Quast Parameters

Parameter	Type	Default	Description
--quast_contig_thresholds	string	0,1000,10000,100000,250000,1000000	Comma-separated list of contig length thresholds

Filtering Parameters

Use these parameters to specify which samples to include or exclude.

Parameter	Type	Default	Description
--include	string		A text file containing sample names (one per line) to include from the analysis
--exclude	string		A text file containing sample names (one per line) to exclude from the analysis

Optional Parameters

These optional parameters can be useful in certain settings.

Parameter	Type	Default	Description
--outdir	string	bactopia	Base directory to write results to

Nextflow Profile Parameters

Parameters to fine-tune your Nextflow setup.

Parameter	Type	Default	Description
--datasets_cache	string	<HOME>/.bactopia/datasets	Directory where downloaded datasets should be stored.

Helpful Parameters

Uncommonly used parameters that might be useful.

Parameter	Type	Default	Description
--wf	string	bactopia	Specify which workflow or Bactopia Tool to execute
--list_wfs	boolean		List the available workflows and Bactopia Tools to use with '--wf'
--help_all	boolean		An alias for --help --show_hidden_params
--version	boolean		Display version text.

Composition

This workflow uses the following subworkflows:

• quast - Evaluate assembly quality using QUAST.

Citations

If you use this in your analysis, please cite the following.

• Bactopia
  Petit III RA, Read TD Bactopia - a flexible pipeline for complete analysis of bacterial genomes. mSystems 5 (2020)

• csvtk
  Shen, W csvtk: A cross-platform, efficient and practical CSV/TSV toolkit in Golang. (GitHub)

• QUAST
  Gurevich A, Saveliev V, Vyahhi N, Tesler G QUAST: quality assessment tool for genome assemblies. Bioinformatics 29, 1072-1075 (2013)

Source

View source on GitHub