How to create a workflow ?

CulebrONT allow you to build a workflow using a simple configuration config.yaml file. In this file :

  • First, provide data paths
  • Second, activate tools from assembly to correction.
  • Third, activate tools from quality checking of assemblies.
  • And last, manage parameters tools.

1. Providing data

First, indicate the data path in the configuration config.yaml file:

DATA:
    FASTQ: '/path/to/fastq/directory/'
    REF: '/path/to/referencefile.fasta'
    GENOME_SIZE: '1m'
    FAST5: '/path/to/fast5/directory/'
    ILLUMINA: '/path/to/illumina/directory/'
    OUTPUT: '/path/to/output/directory/'

Find here a summary table with description of each data need to lauch CulebrONT :

Input Description
FASTQ Every FASTQ file should contain the whole set of reads to be assembled. Each fastq file will be assembled independently
REF Only one REFERENCE genome file will be used by CulebrONT. This REFERENCE will be used for quality steps (ASSEMBLYTICS, QUAST and MAUVE)
GENOME_SIZE Estimated genome size of the assembly can be done on mega (Mb), giga(Gb) or kilobases (Kb). This size is used on some assemblers (CANU) and also on QUAST quality step
FAST5 Nanopolish needs FAST5 files to training steps. Please give the path of FAST5 folder in the FAST5 DATA parameter. Inside this directory, a subdirectory with the exact same name as the corresponding FASTQ (before the .fastq.gz) is requested. For instance, if in the FASTQ directory we have run1.fastq.gz and run2.fastq.gz, CulebrONT is expecting the run1/ and run2/ subdirectories in the FAST5 main directory
ILLUMINA Indicate the path to the directory with Illumina sequence data (in fastq or fastq.gz format) to perform KAT quality. Use preferentially paired-end data. All fastq files need to be homogeneous on their extension name
OUTPUT output path directory

Warning

For FASTQ, naming convention accepted by CulebrONT is NAME.fastq.gz or NAME.fq.gz or NAME.fastq or NAME.fq

All fastq files have to be homogeneous on their extension and can be compressed or not.

Reference fasta file need a fasta or fa extension uncompressed.

2. Chose assemblers, polisher and correctors

Activate/deactivate assemblers, polishers and correctors as you wish. Feel free to activate only assembly, assembly+polishing or assembly+polishing+correction.

Note

If you are working on prokaryote, is recommendated to activate CIRCULAR steps

Example:

ASSEMBLY :
    CANU : False
    FLYE : True
    MINIASM : True
    RAVEN : False
    SMARTDENOVO :  False
    SHASTA : False

POLISHING :
    RACON : True

CIRCULAR : True

CORRECTION :
    NANOPOLISH : False
    MEDAKA : True
    PILON : True

3. Chose quality tools

With CulebrONT you can use several quality tools to check assemblies.

  • If BUSCO or QUAST are used, every fasta generated on the pipeline will be used with them.
  • If BLOBTOOLS, ASSEMBLYTICS, WEESAM and KAT are activated only the last draft generated on the pipeline will be used.
  • KAT quality tool can be activate but Illumina reads are mandatory in this case. These reads can be compressed or not.
# BUSCO and QUAST will be launched on all activated steps (ASSEMBLY, POLISHING, CORRECTION)
QUALITY:
    BUSCO: True
    QUAST: True
#### Others quality tools are lauched only in last assemblies
    WEESAM: True
    BLOBTOOLS: True
    ASSEMBLYTICS: True
#### Others quality softs but illumina reads are required

Alignment of various assemblies for small genomes (<10-20Mbp) is also possible by using Mauve.

  • If you want to improve alignment with MAUVE on circular molecules is recommended to activate Fixstart step.
  • Only activate MAUVE if you have more than one sample and more than one quality step.
#### Alignment of the various assemblies derived from a fastq file for small genomes (<10-20Mbp);

4. Parameters for some specific tools

You can manage tools parameters on the params section on config.yaml file.

Specifically to Racon:

  • Racon can be launch recursively from 1 to 9 rounds. 2 or 3 are recommended.

Specifically to Medaka:

  • If ‘MEDAKA_TRAIN_WITH_REF’ is activated, Medaka launchs training using the reference found in ‘DATA/REF’ param. Medaka does not take into account other medaka model parameters.
  • If ‘MEDAKA_TRAIN_WITH_REF’ is deactivated, Medaka does not launch training but uses instead the model provided in ‘MEDAKA_MODEL_PATH’. Give to CulebrONT path of medaka model in order to correct assemblies. This parameter could not be empty.

Important

Medaka models can be downloaded from the medaka repository. You need to install git lfs (see documentation here https://git-lfs.github.com/) to download largest files before git clone https://github.com/nanoporetech/medaka.git\.

Here you find standard parameters used on CulebrONT. Feel free to adapt it to your requires.

############ PARAMS ################
params:
    #### ASSEMBLY
    MINIMAP2:
        PRESET_OPTION: 'map-ont' # -x minimap2 preset option is map-pb by default (map-pb, map-ont etc)
    FLYE:
        OPTIONS: ''
    CANU:
        MAX_MEMORY: '50G'
        OPTIONS: '-fast'
    SMARTDENOVO:
        KMER_SIZE: 16
        OPTIONS: '-J 5000'
    SHASTA:
        MEM_MODE: 'filesystem'
        MEM_BACKING: 'disk'
        OPTIONS: '--Reads.minReadLength 0'


    #### CIRCULAR
    CIRCLATOR:
        OPTIONS: ''


    #### POLISHING
    RACON:
        RACON_ROUNDS: 2                 #1 to 9


    #### CORRECTION
    CORRECTION_MAKERANGE:
        SEGMENT_LEN: '50000'            # segment length to split assembly and correct it  default=50000
        OVERLAP_LEN: '200'              # overlap length between segments  default=200
    
    NANOPOLISH:
        OPTIONS: ''
    
    MEDAKA:
        MEDAKA_TRAIN_WITH_REF: False    # if 'MEDAKA_TRAIN_WITH_REF' is True, training uses reference found in DATA REF param. 
        
        # Medaka does not take in count other parameters below if MEDAKA_TRAIN_WITH_REF is TRUE.
        MEDAKA_MODEL_PATH: './Data-Xoo-sub/medaka-models/r941_min_high_g303_model.hdf5' # if empty this param is forgotten.
        MEDAKA_FEATURES_OPTIONS: '--batch_size 10 --chunk_len 100 --chunk_ovlp 10'
        MEDAKA_TRAIN_OPTIONS: '--batch_size 10 --epochs 500 '
        MEDAKA_CONSENSUS_OPTIONS: '--batch 200 '

    PILON:
        PILON_ROUNDS: 2                 #1 to 9
        OPTIONS: ''


    #### QUALITY
    BUSCO:
        DATABASE : './Data-Xoo-sub/bacteria_odb10'
        MODEL : 'genome'
        SP : ''                         #--augustus-specie parametter on busco
    
    QUAST:
        GFF: ''
        OPTIONS : '--large'

    DIAMOND:
        DATABASE: './Data-Xoo-sub/testBacteria.dmnd'
    
    MUMMER:
        MINMATCH : 100                  # is -l option with default 20 on MUMMER
        MINCLUSTER: 500                 # is -c option with default 65 on MUMMER
    
    ASSEMBLYTICS:
        UNIQUE_ANCHOR_LEN: 10000
        MIN_VARIANT_SIZE: 50
        MAX_VARIANT_SIZE: 10000

Warning

Please check documentation of each tool and make sure that the settings are correct!

How to run the workflow ?

Command line

Before lauch culebrONT please be sure you have already modified the config.yaml file as was explained on 1. Providing data

This is the recommended Snakemake command line to run CulebrONT:

snakemake --nolock --use-conda --use-singularity --singularity-args '--bind $HOME' --cores -p -s Snakefile --latency-wait 6000000 --keep-going --restart-times 0 --rerun-incomplete --configfile config.yaml --conda-prefix $PWD/build_conda_envs

config.yaml file is give to Snakemake by the argument --configfile

To launch CulebrONT, you should use the parameters --use-singularity and --use-conda. Please don’t forget to export conda on your $PATH.

Snakemake compiles in each output directory conda environment. To avoid this, please use --conda-prefix /path/to/build_conda_env on snakemake command line.

Bind mount disks to singularity environment by using --singularity-args '--bind $YOURMOUNTDISK'. It allows to detect others disk inside of the singularity container. $YOURMOUNTDISK corresponds to mount disk, it could be $HOME or another disk path.

Note

For others snakemake arguments, please check documentation https://snakemake.readthedocs.io/en/v5.11.0/executing/cli.html#all-options

Cluster execution

This is a typical launcher for using CulebrONT on a SLURM cluster. You have to adapt it for the configuration of your favorite one. You can use wrappers or profiles.

wrappers

A slurm_wrapper.py script is available on CulebrONT projet to manage resources from your cluster configuration (from cluster_config.yaml file). This is the easier way to know what is running on cluster and to adapt resources for every job. Take care, this cluster_config.yaml file is becoming obsolete on latest Snakemake versions.

#!/bin/bash
#SBATCH --job-name culebrONT
#SBATCH --output slurm-%x_%j.log
#SBATCH --error slurm-%x_%j.log

module load system/singularity/3.3.0
module load system/python/3.7.2

snakemake --unlock

# SLURM JOBS WITH USING WRAPPER
snakemake --nolock --use-conda --use-singularity --cores -p -s Snakefile --latency-wait 60000000 --keep-going --restart-times 0 --rerun-incomplete --configfile config.yaml --cluster "python3 slurm_wrapper.py config.yaml cluster_config.yaml" --cluster-config cluster_config.yaml --cluster-status "python3 slurm_status.py"

Note

If you have filled in the module load environment “ENVMODULE” on tools_path.yaml file, don’t forget to use –use-envmodules parameter in the snakemake command line !

profiles

Optionally is possible to use Profiles in order to run CulebrONT on HPC cluster. Please follow the recommendations found on the SnakeMake profile github.

#!/bin/bash
#SBATCH --job-name culebrONT
#SBATCH --output slurm-%x_%j.log
#SBATCH --error slurm-%x_%j.log

module load system/singularity/3.3.0
module load system/python/3.7.2

snakemake --unlock

# USING PROFILES
snakemake --nolock --use-singularity --use-conda --cores -p -s Snakefile --configfile config.yaml --latency-wait 60000000 --keep-going --restart-times 0 --rerun-incomplete --cluster-config cluster_config.yaml --profile slurm-culebrONT

Note

For others snakemake cluster arguments, please check documentation https://snakemake.readthedocs.io/en/stable/executing/cluster.html

In any case, this launcher can be submitted to the SLURM queue typing:

sbatch submit_culebront.sh

Output on CulebrONT

The architecture of CulebrONT output is designed as follows:

OUTPUT_CULEBRONT_CIRCULAR/
├── SAMPLE-1
│   ├── AGGREGATED_QC
│   │   ├── DATA
│   │   ├── MAUVE_ALIGN
│   │   └── QUAST_RESULTS
│   ├── ASSEMBLERS
│   │   ├── CANU
│   │   │   ├── ASSEMBLER
│   │   │   ├── CORRECTION
│   │   │   ├── FIXSTART
│   │   │   ├── POLISHING
│   │   │   └── QUALITY
│   │   ├── FLYE
│   │   │   ├── ...
│   │   ├── MINIASM
│   │   │   ├── ...
│   │   ├── RAVEN
│   │   │   ├── ...
│   │   ├── SHASTA
│   │   │   ├── ...
│   │   └── SMARTDENOVO
│   │   │   ├── ...
│   ├── DIVERS
│   │   └── FASTQ2FASTA
│   ├── LOGS
│   └── REPORT
└── FINAL_REPORT
├── SAMPLE-2 ...

Report

CulebrONT generates a useful report containing, foreach fastq, a summary of interesting statistics. Please discover an example … and enjoy !!

Important

To visualise the report created by CulebrONT, transfer the folder FINAL_RESULTS on your local computer and open it on a navigator.