Building a Reproducible Bacterial Genomics Workflow with Snakemake
By Dr. Zubair Khalid, DVM, MS, PhD ·

Quick Answer
- Build a reproducible bacterial genomics pipeline by structuring Snakemake rules for read QC, assembly, and annotation with explicit configuration files.
- Start with a minimal working template that processes one sample pair, then scale to batch analysis using Snakemake wildcards and cluster execution.
- Reproducibility depends on pinning software versions and container images, but biological variation in sequencing data still requires manual inspection of QC metrics.
At a Glance
| Workflow Stage | Core Tool Category | Key Decision Point | Common Output |
|---|---|---|---|
| Read quality control | Trimming and filtering tools | Set minimum read length and quality thresholds based on your sequencing platform | Cleaned FASTQ files and QC reports |
| Genome assembly | Assembler such as SPAdes or SKESA | Choose assembly strategy based on read length and coverage depth | Contigs in FASTA format |
| Genome annotation | Prokka or Bakta | Select reference database matching your organism of interest | Annotated GFF3, GenBank, and protein FASTA files |
Pipeline Design Considerations
| Design Aspect | Option A | Option B | Decision Criterion |
|---|---|---|---|
| Environment management | Conda environments per rule | Singularity or Docker containers | Reproducibility requirements and cluster compatibility |
| Configuration approach | Single YAML file | Per-sample CSV plus global config | Number of samples and metadata complexity |
| Execution mode | Local execution | Cluster submission with SLURM or SGE | Compute resources and sample batch size |
Scope of Bacterial Genomics Workflows
Bacterial genomics workflows transform raw sequencing reads into biologically interpretable results. The core analytical path includes quality trimming, genome assembly, and functional annotation. These steps produce the foundational data used for downstream analyses such as antimicrobial resistance gene detection, phylogenetic placement, and outbreak investigations.
The World Health Organization describes antimicrobial resistance as a global public health concern that requires surveillance and stewardship. Genomic workflows support these surveillance efforts by providing high-resolution data on bacterial populations. For laboratory professionals, a reproducible workflow ensures that results generated today can be compared with results generated months later or in another facility.
The American Society for Microbiology emphasizes that microbiology laboratory practice requires rigorous quality control and standardized methods. A Snakemake workflow addresses this requirement by automating pipeline steps and recording the exact parameters used for each analysis. This documentation function is as important as the analysis itself because it allows other researchers to verify and reproduce your findings.
Core Principles of Reproducible Workflows
Workflow Management Systems
Snakemake is a workflow management system that organizes analysis steps into rules. Each rule defines an input, an output, and a shell command or Python script that transforms the input into the output. The system tracks which files have been generated and only reruns rules when inputs change. This incremental execution saves compute time and ensures that results are traceable.
The key advantage of a workflow manager over a collection of scripts is the automatic handling of dependencies. When you update a parameter in your configuration file, Snakemake identifies which rules need to be rerun and executes them in the correct order. This prevents the common problem of running an analysis with mismatched input files or outdated parameters.
Configuration Management
A configuration file separates the analysis parameters from the workflow logic. This allows you to change thresholds, database paths, or tool versions without editing the core workflow code. The configuration file should contain all parameters that might vary between runs, including:
- Input file paths and sample names
- Quality control thresholds
- Assembly parameters
- Annotation database selections
- Output directory structure
The configuration file also serves as a record of the analysis parameters. When you revisit a project months later, the configuration file tells you exactly what settings were used. This is essential for reproducing results and for comparing analyses across different sample batches.
Software Version Control
Bioinformatics tools change frequently, and different versions can produce different results. A reproducible workflow must record the exact version of every tool used. Snakemake supports this through environment modules, conda environments, or container images. Each rule can specify its own environment, ensuring that the correct tool version is used for each step.
Container images provide the strongest reproducibility guarantee because they include the operating system, libraries, and tools in a single package. This eliminates the variability that can arise from different system configurations. For laboratory settings that require strict version control, containers are the preferred approach.
Building the Workflow Structure
Project Directory Layout
A well-organized project directory makes the workflow easier to maintain and share. The recommended structure separates the workflow code from the data and results:
project/
├── config/
│ └── config.yaml
├── workflow/
│ ├── Snakefile
│ └── rules/
│ ├── qc.smk
│ ├── assembly.smk
│ └── annotation.smk
├── data/
│ └── raw_reads/
├── results/
│ ├── qc/
│ ├── assemblies/
│ └── annotations/
└── logs/
This structure keeps the workflow code separate from the data and results. The config directory contains the parameters, the workflow directory contains the rules, and the results directory contains the outputs. The logs directory stores the standard output and error messages from each rule.
The Snakefile
The Snakefile is the entry point for the workflow. It defines the overall structure and includes the rule files. A minimal Snakefile looks like this:
configfile: "config/config.yaml"
include: "workflow/rules/quality.smk"
include: "workflow/rules/assembly.smk"
include: "workflow/rules/annotation.smk"
rule all:
input:
expand("results/annotations/{sample}.gff", sample=config["samples"])
The rule all defines the final target of the workflow. Snakemake works backward from this target to determine which rules need to be executed. The expand function creates a list of expected output files based on the sample names in the configuration file.
Configuration File Structure
The configuration file defines the samples and parameters for the analysis. A basic configuration file contains:
samples:
- sample1
- sample2
- sample3
reads:
sample1: ["data/raw/sample1_R1.fastq.gz", "data/raw/sample1_R2.fastq.gz"]
sample2: ["data/raw/sample2_R1.fastq.gz", "data/raw/sample2_R2.fastq.gz"]
trim:
min_length: 50
quality_threshold: 20
assembly:
min_contig_length: 500
annotation:
database: "prokka_db"
This configuration file defines the samples, the read file paths, and the parameters for each analysis step. The workflow rules read these values and use them to execute the analysis.
Quality Control Rules
Read Trimming and Filtering
Raw sequencing reads contain adapter sequences and low-quality bases that can interfere with assembly and annotation. The quality control step removes these artifacts and produces clean reads for downstream analysis.
The trimming rule takes the raw reads and produces trimmed reads. The rule should specify the trimming tool, the quality threshold, and the minimum read length. The output is a pair of trimmed FASTQ files for each sample.
rule trim_reads:
input:
r1=config["reads"][sample],
r2=config["reads"][sample][1]
output:
r1="results/qc/{sample}_R1_trimmed.fastq.gz",
r2="results/qc/{sample}_R2_trimmed.fastq.gz"
params:
min_quality=config["qc"]["quality_threshold"],
min_length=config["qc"]["min_length"]
shell:
"trimmomatic PE {input.r1} {input.r2} {output.r1} {output.r2} "
"LEADING:{params.min_quality} TRAILING:{params.min_quality} "
"SLIDINGWINDOW:4:{params.min_quality} MINLEN:{params.min_length}"
The rule uses the configuration values for the quality threshold and minimum length. This allows you to adjust the parameters without editing the rule code.
Quality Assessment
After trimming, the workflow should generate a quality report for each sample. The report provides a visual summary of the read quality, including base quality scores, GC content, and sequence duplication levels. This report is the first check on whether the sequencing data is suitable for assembly.
The quality report rule should run after the trimming rule and produce an HTML report for each sample. The report should be stored in the results directory and should be reviewed by the researcher before proceeding to assembly.
Assembly Rules
Genome Assembly
Genome assembly reconstructs the bacterial genome from the trimmed reads. The assembly rule takes the trimmed reads and produces a set of contigs. The choice of assembler depends on the sequencing platform and the expected genome size.
For short-read data, the assembly rule should specify the assembler and the expected genome size. The assembler produces a FASTA file containing the contigs. The rule should also specify the minimum contig length to filter out short, unreliable contigs.
rule assemble:
input:
r1="results/qc/{sample}_R1_trimmed.fastq.gz",
r2="results/qc/{sample}_R2_trimmed.fastq.gz"
output:
"results/assemblies/{sample}_contigs.fasta"
params:
genome_size=config["assembly"]["genome_size"],
min_contig=config["assembly"]["min_contig_length"]
conda:
"envs/assembly.yaml"
shell:
"spades.py --isolate -1 {input.r1} -2 {input.r2} "
"-o {output} --meta"
Assembly Quality Assessment
Assembly quality assessment is a critical step that is often overlooked. The workflow should include a rule that calculates assembly statistics such as the number of contigs, the N50 value, and the total assembly length. These statistics provide a quantitative measure of assembly quality.
The assembly quality report should be compared to the expected genome size for the organism. A large discrepancy between the expected and observed genome size indicates a problem with the assembly or the input data.
Annotation Rules
Genome Annotation
Genome annotation identifies the functional elements in the assembled genome. The annotation rule uses the assembled contigs and a reference database to predict genes, transfer RNA genes, and other functional elements.
The annotation rule should specify the annotation tool and the database. The output is a set of files including the annotated GenBank file, the GFF file, and the protein sequences. These files are the primary output of the workflow and are used for downstream analysis.
The annotation rule should also specify the organism type. Some annotation tools have specific settings for bacteria that improve the accuracy of gene prediction.
Annotation Quality Control
The annotation output should be checked for basic quality indicators. The number of predicted genes should be within the expected range for the organism. The number of transfer RNA genes should also be checked. An unusually low number of transfer RNA genes can indicate a problem with the assembly or the annotation.
The workflow should produce a summary report that lists the annotation statistics for each sample. This report allows the researcher to quickly identify samples that need further investigation.
Configuration and Customization
Sample Configuration
The configuration file should be structured to make it easy to add new samples. Each sample should have a unique identifier and the paths to its raw reads. The workflow uses these identifiers to name the output files.
For large projects, the configuration file can be generated from a spreadsheet or a sample sheet. This reduces the risk of manual errors when adding many samples to the workflow.
Parameter Tuning
The configuration file allows the researcher to adjust the analysis parameters without modifying the workflow code. This is important for optimizing the workflow for different organisms or sequencing platforms.
For example, the quality threshold for trimming can be adjusted based on the sequencing platform. The assembly parameters can be adjusted based on the expected genome size and coverage. The annotation database can be changed based on the organism.
Adding New Rules
The modular structure of the workflow makes it easy to add new analysis steps. A new rule can be added to the rules directory and included in the Snakefile. The rule should define its inputs and outputs, and the workflow will automatically handle the dependencies.
For example, a rule for antimicrobial resistance gene detection can be added after the annotation step. The rule would take the annotated files as input and produce a report of detected resistance genes.
Execution and Monitoring
Local Execution
The workflow can be executed on a local machine for small projects. The command snakemake -p runs the workflow and prints the commands that are executed. The -n flag performs a dry run that shows the rules that would be executed without actually running them.
The dry run is useful for checking the workflow structure before running the full analysis. It shows the order of the rules and the files that will be created.
Cluster Execution
For large projects, the workflow can be executed on a cluster. Snakemake supports cluster execution through the --cluster option. The cluster configuration specifies the scheduler and the resources required for each rule.
The cluster execution requires a cluster configuration file that specifies the number of cores, the memory, and the runtime for each rule. The workflow submits each rule as a separate job to the cluster scheduler.
Monitoring Progress
Snakemake provides a report file that summarizes the workflow execution. The report shows the rules that were executed, the files that were created, and the time and resources used. This report is useful for tracking the progress of the workflow and for identifying bottlenecks.
The report also shows the rule dependencies and the execution order. This is useful for understanding the workflow structure and for identifying rules that can be optimized.
Common Failure Patterns
Input File Errors
The most common failure is incorrect input file paths. The workflow will fail if the input files are not found. The error message will indicate the missing file and the rule that requires it.
The solution is to check the configuration file and ensure that the file paths are correct. The file paths should be relative to the workflow directory or absolute paths.
Software Version Conflicts
Software version conflicts can cause the workflow to fail or produce incorrect results. The workflow should use containers or conda environments to ensure that the correct software versions are used.
The error message will indicate the software that failed and the version that was used. The solution is to update the environment file to specify the correct version.
Memory and Compute Limits
The workflow can fail if the compute resources are insufficient. The assembly step is the most resource-intensive step and can require significant memory. The cluster configuration should specify the memory and compute requirements for each rule.
The error message will indicate the resource that was exceeded. The solution is to increase the resource allocation or to optimize the rule to use fewer resources.
Quality Control and Validation
Reference Materials
The use of authenticated reference materials is essential for validating the workflow. The American Type Culture Collection provides authenticated bacterial strains that can be used as positive controls. These strains have known genomic sequences and can be used to verify that the workflow produces correct results.
The workflow should include a rule for processing a reference sample. The reference sample should be processed through the entire workflow, and the results should be compared to the known genome sequence.
Reproducibility Testing
The workflow should be tested for reproducibility by running the same sample multiple times. The results should be identical for each run. The workflow should also be tested on different machines to ensure that the results are consistent.
The reproducibility test should be documented and the results should be recorded. This documentation is important for demonstrating the reliability of the workflow.
Validation Records
The workflow should produce a validation report that records the parameters and the results for each run. The report should include the software versions, the configuration parameters, and the quality metrics. This report is the primary record for the analysis.
The validation report should be stored with the results and should be accessible for future reference. The report should be updated whenever the workflow is run.
Biosafety and Data Management
Biosafety Considerations
The CDC and NIH Biosafety in Microbiological and Biomedical Laboratories provides the framework for risk assessment and containment in microbiology laboratories. Genomic analysis of bacterial pathogens requires careful consideration of biosafety. The workflow should be designed to handle data from organisms that require specific containment levels.
The workflow should include a step for recording the biosafety level of each sample. This information should be included in the configuration file and should be considered when handling the data.
Data Storage and Backup
The workflow produces large amounts of data. The raw reads, the trimmed reads, the assemblies, and the annotations should be stored in a structured directory. The data should be backed up regularly to prevent data loss.
The workflow should include a rule for archiving the results. The archive should include the configuration file, the workflow code, and the results. This archive is the complete record of the analysis.
Data Sharing
The workflow results should be shared in a format that is accessible to other researchers. The annotation files and the assembly files should be shared in standard formats. The workflow code and the configuration file should be shared to allow other researchers to reproduce the analysis.
The American Society for Microbiology provides guidance on data sharing and professional practice in microbiology. The workflow should follow these guidelines to ensure that the data is shared responsibly.
Limitations and Professional Escalation
Workflow Limitations
The workflow has limitations that should be acknowledged. The workflow is designed for bacterial genomes and may not be suitable for other organisms. The workflow assumes that the input data is of sufficient quality for assembly.
The workflow does not replace the need for expert review. The results should be reviewed by a researcher with experience in bacterial genomics. The workflow provides the data, but the interpretation requires expertise.
Professional Escalation Criteria
The workflow results should be escalated to a professional if the results are unexpected or if the quality metrics are outside the expected range. The escalation criteria include:
- The assembly quality metrics are significantly worse than expected
- The annotation results are inconsistent with the organism
- The quality control reports indicate a problem with the data
The escalation should include the workflow results and the configuration file. The professional should review the results and determine the appropriate action.
A Practical Decision Framework for Workflow Parameter Selection
Bioinformaticians often struggle with the transition from a working pipeline to one that produces biologically meaningful results for their specific bacterial species and sequencing platform. The default parameters in most tools are generic starting points, not optimized settings. This section provides a structured decision framework for selecting parameters, a record system for tracking those decisions, and a troubleshooting method for when results fall outside expected ranges.
The Parameter Decision Matrix
The first step in building a reproducible workflow is recognizing that every parameter choice involves a tradeoff. A decision matrix helps you document these tradeoffs and make consistent choices across samples and projects. The matrix should be completed before you run the workflow on your full sample set, using a small pilot set of two to three representative samples.
| Parameter | Default Starting Point | Decision Question | Data Source for Decision | Adjustment Direction |
|---|---|---|---|---|
| Minimum read length after trimming | 50 bases | What is the read length distribution of your raw data? | FastQC per-base sequence quality plot | Increase if reads are long and high quality, decrease if reads are short |
| Quality threshold for trimming | Q20 | What is the error rate you can tolerate for your downstream analysis? | Phred score distribution from FastQC | Increase to Q30 for variant calling, decrease to Q15 for assembly only |
| Minimum contig length | 500 bp | What is the expected genome size and repeat structure of your organism? | Known reference genome statistics | Increase for closed genomes, decrease for draft assemblies |
| Genome size estimate for assembler | 5 Mb | What is the expected genome size of your organism? | Literature values or reference genome | Adjust to within 10 percent of expected size |
| Annotation database | Default for the tool | What is the taxonomic classification of your organism? | 16S rRNA identification or MALDI-TOF result | Select the closest matching genus or family database |
The decision matrix should be stored in the project directory as a CSV or Markdown file. This file becomes part of the project record and is referenced in the workflow report. The matrix is not a static document. It is updated when you process a new organism type or switch sequencing platforms.
Step-by-Step Parameter Selection Process
The parameter selection process follows a structured sequence that prevents arbitrary choices. Each step produces a record that feeds into the next step.
Step 1: Characterize the input data. Run FastQC on two to three raw read pairs before configuring the workflow. Record the total read count, read length distribution, GC content, and duplication level. This information determines the initial trimming parameters. For example, if the read length is 150 bases and the quality drops below Q20 only in the final 10 bases, the trailing trimming threshold can be set to Q20 with a sliding window of 4 bases.
Step 2: Determine the expected genome characteristics
The expected genome size and GC content of your organism come from the literature or from a reference genome. The American Type Culture Collection provides authenticated strain information that includes genome size and growth characteristics. This information is used to set the assembly parameters and to validate the final assembly. The expected genome size is also used to estimate the coverage depth from the read count.
Step 3: Run a pilot assembly
Run the assembly rule on one sample with the default parameters. Record the assembly statistics including the number of contigs, N50, and total assembly length. Compare these statistics to the expected genome size. If the total assembly length is within 10 percent of the expected genome size and the N50 is above 50,000 bases for a typical bacterial genome, the default parameters are acceptable. If the assembly is fragmented, adjust the minimum contig length and the assembler options.
Step 4: Validate with a reference strain
If a reference strain is available, process it through the entire workflow. The American Type Culture Collection provides authenticated strains with known genome sequences. The assembly of the reference strain should match the known genome sequence with high identity. This validation step confirms that the workflow parameters are appropriate for your organism type.
Step 5: Document the final parameters
Once the pilot analysis is complete, record the final parameters in the configuration file and in the decision matrix. The configuration file is the machine-readable record, and the decision matrix is the human-readable explanation of why each parameter was chosen.
The Parameter Record System
A parameter record system is a structured way to track the decisions made for each project and each sample batch. The system has three components: the configuration file, the decision matrix, and the run log.
The configuration file stores the active parameters for the current run. The decision matrix stores the rationale for each parameter choice. The run log records the actual parameters used for each execution, including the software versions and the date.
The run log is generated automatically by Snakemake. Each rule execution records the command, the input files, the output files, and the software version. The run log is stored in the logs directory and is named with the date and the sample identifier.
The parameter record system serves two purposes. First, it allows you to reproduce a specific analysis by restoring the exact configuration and software versions. Second, it allows you to compare analyses across different parameter sets to understand how parameter choices affect the results.
Troubleshooting Method for Unexpected Results
When the workflow produces results that fall outside the expected range, a structured troubleshooting method is needed. The method follows a sequence of checks that isolate the cause of the problem.
Check 1: Verify the input data quality
The first check is the raw read quality. If the raw reads have high duplication levels, low complexity, or adapter contamination, the trimming step may not remove all artifacts. The FDA Bacteriological Analytical Manual provides context on the quality of sequencing data generated from food and environmental samples. The quality report for each sample should be reviewed before the assembly step.
Check 2: Verify the assembly statistics
The assembly statistics are compared to the expected genome size and the expected number of contigs. A typical bacterial genome assembly from short reads produces 50 to 200 contigs. If the assembly has more than 500 contigs, the input data may be contaminated or the coverage may be too low. If the assembly has fewer than 20 contigs, the genome may be a small plasmid or the assembly may have collapsed repetitive regions.
Check 3: Check for contamination
Contamination is a common cause of unexpected assembly results. The GC content of the assembly should match the expected GC content of the target organism. The coverage depth can also indicate contamination. If the coverage is highly variable across the genome, the sample may contain multiple organisms. The CDC and NIH Biosafety in Microbiological and Biomedical Laboratories provides guidance on handling samples that may contain multiple organisms.
Check 4: Verify the annotation completeness
The annotation statistics are compared to the expected values for the organism. A typical bacterial genome has 4000 to 6000 protein coding genes and 40 to 60 transfer RNA genes. If the number of protein coding genes is below 3000, the assembly may be incomplete. If the number of transfer RNA genes is below 20, the annotation may have failed to identify these features.
Check 5: Compare to a reference
The final check is to compare the assembly to a reference genome. The American Type Culture Collection provides reference genomes for many bacterial species. The comparison can be done using a whole genome alignment tool or by comparing the gene content. The comparison identifies regions that are missing or rearranged in the assembly.
Common Failure Patterns and Their Resolution
The troubleshooting method addresses the most common failure patterns in bacterial genomics workflows. Each failure pattern has a specific cause and a specific resolution.
Failure pattern 1: Low assembly N50
A low N50 indicates that the assembly is fragmented. The cause is often low coverage or high repeat content. The resolution is to increase the coverage by sequencing more deeply or to adjust the assembler parameters. The assembly parameters can be adjusted to use a more sensitive mode that is designed for low coverage data.
Failure pattern 2: High number of contigs
A high number of contigs indicates that the assembly is fragmented or that the sample is contaminated. The resolution is to check the input data for contamination and to increase the minimum contig length. The minimum contig length filters out short contigs that are likely to be assembly artifacts.
Failure pattern 3: Missing genes in the annotation
Missing genes in the annotation indicate that the assembly is incomplete or that the annotation database is not appropriate for the organism. The resolution is to check the assembly completeness and to select a more specific annotation database. The American Society for Microbiology provides guidance on the selection of annotation databases for different bacterial groups.
Failure pattern 4: Unexpected genome size
An unexpected genome size indicates that the assembly is either too large or too small. A genome that is too large may be contaminated with another organism. A genome that is too small may have collapsed repetitive regions or may be missing a plasmid. The resolution is to check the coverage and the GC content of the assembly.
The Role of Reference Materials in Parameter Selection
Reference materials are essential for validating the parameter selection process. The American Type Culture Collection provides authenticated bacterial strains that have been characterized by whole genome sequencing. These strains are used as positive controls in the workflow.
The reference strain is processed through the entire workflow with the same parameters as the test samples. The assembly of the reference strain is compared to the known genome sequence. The comparison should show high identity and complete coverage. If the reference strain does not assemble correctly, the parameters are not appropriate for the target organism.
The reference strain also serves as a control for the annotation step. The annotation of the reference strain should identify the same genes as the known annotation. If the annotation is missing genes or has extra genes, the annotation database or the annotation parameters need to be adjusted.
The Relationship Between Parameters and Reproducibility
The parameter record system is the foundation of reproducibility. A reproducible workflow is one that produces the same results when run with the same input data and the same parameters. The parameter record system ensures that the parameters are recorded and can be retrieved for future runs.
The World Health Organization emphasizes the importance of standardized methods for antimicrobial resistance surveillance. The parameter record system supports this standardization by providing a clear record of the methods used for each analysis. This record is essential for comparing results across different laboratories and across different time periods.
The parameter record system also supports the professional practice of microbiology. The American Society for Microbiology emphasizes the importance of documentation and quality control in the laboratory. The parameter record system provides the documentation that is required for professional practice.
Practical Implementation Steps
The decision framework is implemented in the following steps.
Step 1: Create the decision matrix file
Create a Markdown file in the config directory that contains the decision matrix. The matrix lists each parameter, the default value, the decision question, and the final value. The matrix is updated as the parameters are finalized.
Step 2: Run the pilot analysis
Run the workflow on two to three samples with the default parameters. Record the quality metrics and the assembly statistics. The pilot analysis is the basis for the parameter decisions.
Step 3: Adjust the parameters
Based on the pilot analysis, adjust the parameters in the configuration file. The adjustments are recorded in the decision matrix. The workflow is rerun on the pilot samples to verify that the adjustments improve the results.
Step 4: Validate with a reference strain
Process a reference strain through the workflow with the final parameters. The reference strain is the validation that the parameters are correct for the target organism.
Step 5: Document the final parameters
Record the final parameters in the configuration file and in the decision matrix. The run log is generated automatically by the workflow and is stored with the results.
Records and Measurements
The decision framework requires specific records and measurements to be maintained. The records are the decision matrix, the configuration file, and the run log. The measurements are the quality metrics, the assembly statistics, and the annotation statistics.
The quality metrics include the read count, the read length, the GC content, and the duplication level. The assembly statistics include the number of contigs, the N50, the total assembly length, and the coverage. The annotation statistics include the number of protein coding genes, the number of transfer RNA genes, and the number of ribosomal RNA genes.
The records and measurements are stored in the results directory. The decision matrix is stored in the config directory. The configuration file is stored in the config directory. The run log is stored in the logs directory.
Professional Escalation Criteria
The decision framework includes specific criteria for escalating to a professional. The escalation criteria are based on the results of the validation steps.
The first escalation criterion is the failure of the reference strain to assemble correctly. If the reference strain does not assemble with the expected statistics, the parameters are not appropriate for the target organism. The analysis should be escalated to a professional who can review the parameters and the input data.
The second escalation criterion is the failure of the annotation to identify the expected genes. If the annotation of the reference strain does not match the known annotation, the annotation database or the parameters need to be reviewed by a professional.
The third escalation criterion is the presence of unexpected results in the test samples. If the assembly statistics are significantly outside the expected range, the sample may be contaminated or the sequencing data may be of poor quality. The analysis should be escalated to a professional who can review the data and the parameters.
The escalation process includes the decision matrix, the configuration file, and the run log. The professional reviews these records and determines the appropriate action. The action may be to adjust the parameters, to re-sequence the sample, or to reject the sample.
Frequently Asked Questions
What is the minimum input data required for the workflow?
The workflow requires paired-end FASTQ files for each sample. The files should be in gzipped format. The workflow also requires a configuration file that lists the samples and the file paths.
How long does the workflow take to run?
The runtime depends on the number of samples and the compute resources. A single sample can take several hours to complete. The runtime is dominated by the assembly step.
Can the workflow be used for other organisms?
The workflow is designed for bacterial genomes. The workflow can be adapted for other organisms by changing the assembly and annotation parameters. The annotation database must be appropriate for the organism.
How do I add a new sample to the workflow?
Add the sample to the configuration file. The sample should have a unique identifier and the paths to the read files. The workflow will automatically process the new sample.
What should I do if the workflow fails?
Check the error message and the log files. The error message will indicate the rule that failed and the reason. The most common issues are incorrect file paths and software version conflicts.
How do I ensure the workflow is reproducible?
Use containers or virtual environments to pin the software versions. Record the configuration parameters and the software versions in the report. Test the workflow on the same sample multiple times to ensure the results are identical.
What is the best way to share the workflow results?
Share the workflow code, the configuration file, and the results. The results should be in standard formats. The workflow code and the configuration file allow other researchers to reproduce the analysis.
How do I handle the data from a biosafety level 3 organism?
The data should be handled according to the biosafety guidelines. The CDC and NIH Biosafety in Microbiological and Biomedical Laboratories provides the framework for risk assessment and containment. The data should be stored and processed in a secure environment.
Related Bacteriology Guides
- Bacterial Contamination of Poultry: Salmonella and E. coli
- Bacterial Diseases of Chickens: A Comprehensive Overview
- Bacterial Growth Dynamics in Chicken: From Farm to Refrigeration
- Bacterial Pathogens in Poultry: Comprehensive Clinical Reference
- Bacterial Poultry Diseases: Comprehensive Overview and Classification
References and Further Reading
- Biosafety in Microbiological and Biomedical Laboratories. CDC and NIH.
This article is educational and does not replace validated laboratory procedures, clinical diagnosis, institutional biosafety review, or public-health guidance.