Burrows-Wheeler Aligner

Introduction

BWA is a software package for mapping low-divergent sequences against a large reference genome, such as the human genome. It consists of three algorithms: BWA-backtrack, BWA-SW and BWA-MEM. The first algorithm is designed for Illumina sequence reads up to 100bp, while the rest two for longer sequences ranged from 70bp to 1Mbp. BWA-MEM and BWA-SW share similar features such as long-read support and split alignment, but BWA-MEM, which is the latest, is generally recommended for high-quality queries as it is faster and more accurate. BWA-MEM also has better performance than BWA-backtrack for 70-100bp Illumina reads.

Installed version

The currently installed versions of BWA are

bwa.kit/0.7.12
This version is installed on the older environment hpc-uniol-env
BWA/0.7.17-intel-2018a
This newer version is installed in the newer environment hpc-env/6.4

Using BWA

If you want to find out more about BWA on the HPC cluster, you can use the command

module spider bwa.kit

This will show you basic informations e.g. a short description and the currently installed version.

Depending on the environment you work on or the version you need, you have either to load

module load bwa.kit

or you have to change to the new environment at first:

module load hpc-env/6.4
module load BWA

Always remember: this commands are case sensitive!

Using BWA with the HPC cluster

If you want to use BWA on the HPC cluster, you will have to create a jobscript which is than processed by SLURM.

An example jobscript could look like this:

#!/bin/bash 

#SBATCH --ntasks=1
#SBATCH --mem=2G
#SBATCH --time=0-2:00  
#SBATCH --job-name=BWA-TEST
#SBATCH --output=bwa-test.%j.out        
#SBATCH --error=bwa-test.%j.err   

##YOUR SCRIPT STARTS HERE
bwa ..

You can find a short manual on how to use BWA here.

Additionally, you can get a quick overview of the available commands, by just typing bwa into the console after loading the module. You will then get a short summary of the commands for bwa'. The new version 0.7.17, which is installed on the environment hpc-env/6.4 does additionally come with a man page. To read it, you have to type in

man bwa

Documentation

For further informations, please visit the official manual.