Another Bisulfite Mapping Algorithm (abismal) is a read mapping program for bisulfite sequencing in DNA methylation studies.

• Binaries for macOS and Linux.
• Latest stable release.
• Quickstart
• Examples
• Full documentation here (2025-06-13 needs an update)
• Building from source

• Download macOS or Linux binaries, install through conda or source.

• Make an index for your reference genome (assuming human hg38):

  ./abismal idx hg38.fa hg38.idx

• Map reads using that index:

  ./abismal map -i hg38.idx -o reads.sam reads_1.fq reads_2.fq

• See documentation for mapping options and output formats.

• Make an index from a reference genome in a single FASTA file (here, hg38.fa):

  ./abismal idx hg8.fa hg38.idx

• Make an index using 8 threads:

  ./abismal idx -t 8 hg38.fa hg38.idx

• Map single-end reads to hg38 using an index:

  ./abismal map -i hg38.idx -o reads.sam reads.fq

• Map single-end reads with 64 cores (and get very close to 64x speedup):

  ./abismal map -i hg38.idx -o reads.sam -t 64 reads.fq

• Map paired-end reads in reads_1.fq and reads_2.fq:

  ./abismal map -i hg38.idx -o reads.sam reads_1.fq reads_2.fq

• Get output in BAM format:

  ./abismal map -i hg38.idx -B -o reads.bam reads.fq

• Get mapping statistics in YAML format:

  ./abismal map -i hg38.idx -s reads.stats.yaml -o reads.sam reads.fq

• Skip making the index (make it on the fly):

  ./abismal map -g hg38.fa -o reads.sam reads.fq

• Map reads from PBAT data:

  ./abismal map -i hg38.idx -P -o reads.sam reads.fq

• Map reads from random PBAT data:

  ./abismal map -i hg38.idx -R -o reads.sam reads.fq

Mapping results are reported in SAM format. Some choices in the output are explicitly highlighted below:

• Reads are output identically to how they appear in the input FASTQ files, regardless of mapped strand.
• the NM tag reports the edit distance between the read and the output, specifically the sum of mismatches, insertions and deletions to the best mapping position.
• The CV tag reports the assumed bisulfite base used to map the read. Reads mapped as A-rich will be reported with CV:A:A, and reads mapped as T-rich will be reported with CV:A:T. This tag is independent of the strand the read was mapped to. If reads are not mapped in PBAT or random PBAT mode, the first end will always be T-rich and the second end will always be A-rich.

If you are here because the binaries don't work for you, please let us know and we'll try to fix that.

These instructions have been tested for Ubuntu 24.04 and Fedora 41. They will likely work on most APT and RPM-based distributions in 2025.

Here are the basic commands if you are ready to build:

wget https://github.com/smithlabcode/abismal/releases/download/v3.3.0/abismal-3.3.0.tar.gz
tar -xf abismal-3.3.0.tar.gz
cd abismal-3.3.0
./configure --prefix=${HOME}
make
make install

If you that doesn't work, then check that you have the right dependencies. You can find them in the lists below, depending on your system.

• Dependencies:

  Ubuntu/Debian

  apt-get update && \
  DEBIAN_FRONTEND=noninteractive \
  apt-get install -y --no-install-recommends \
      ca-certificates \
      g++ \
      make \
      zlib1g-dev \
      libhts-dev \
      automake \
      git \
      wget

  Fedora/Red Hat

  dnf update -y && \
  dnf install -y \
      g++ \
      make \
      zlib-devel \
      libhts-devel \
      wget \
      automake \
      awk \
      git

  The wget is only needed if for the next step, and the automake and git (and awk for Fedora/Red Hat) are only needed for the subsequent step using a clone. Your machine likely has these already.

  If you don't have admin privileges on your system, you can use Conda to get all the dependencies. Assuming you don't already have conda installed, this will get everything you need:

  wget https://github.com/conda-forge/miniforge/releases/latest/download/Miniforge3-Linux-x86_64.sh && \
  sh Miniforge3-Linux-x86_64.sh -bsup ${HOME}/miniforge3 && \
  export PATH=${HOME}/miniforge3/bin:$PATH && \
  conda install -y \
      conda-forge::binutils \
      conda-forge::gxx \
      conda-forge::zlib \
      conda-forge::make \
      conda-forge::automake \
      conda-forge::git \
      bioconda::htslib

• Build from a source release and install in your home directory:

  wget https://github.com/smithlabcode/abismal/releases/download/v3.3.0/abismal-3.3.0.tar.gz
  tar -xf abismal-3.3.0.tar.gz
  cd abismal-3.3.0
  ./configure --prefix=${HOME}
  make
  make install

• Build from a clone and install in your home directory:

  git clone --recursive https://github.com/smithlabcode/abismal.git
  cd abismal
  ./autogen.sh
  ./configure --prefix=${HOME}
  make
  make install

• Dependencies:

  Get a compiler through xcode or get gcc from Homebrew by adding gcc to the list below.

  brew update && \
  brew install \
      zlib \
      htslib \
      automake \
      git \
      wget

  The wget is only needed if for the next step, and the automake and git are only needed for the subsequent step using a clone. I tested these steps on GitHub runners for macOS-15 so you might need additional dependencies.

  Conda as explained above will also work, but you need the conda installer script for your macOS system.

• Build from a source release and install in your home directory:

  wget https://github.com/smithlabcode/abismal/releases/download/v3.3.0/abismal-3.3.0.tar.gz
  tar -xf abismal-3.3.0.tar.gz
  cd abismal-3.3.0
  ./configure CPPFLAGS="-I$(brew --prefix)/include" LDFLAGS="-L$(brew --prefix)/lib" --prefix=${HOME}
  make
  make install

• Build from a clone and install in your home directory:

  git clone --recursive https://github.com/smithlabcode/abismal.git
  cd abismal
  ./autogen.sh
  ./configure CPPFLAGS="-I$(brew --prefix)/include" LDFLAGS="-L$(brew --prefix)/lib" --prefix=${HOME}
  make
  make install

If you build from source you can enable a mode for mapping very short reads. Using such reads is discouraged and rarely helpful. Use the --help argument to the configure script to see how to enable this option.

Andrew D Smith andrewds@usc.edu

The abismal manuscript is available here. If you used abismal to analyze your data, please cite:

de Sena Brandine, G., & Smith, A. D. (2021).
Fast and memory-efficient mapping of short bisulfite sequencing reads using a two-letter alphabet.
NAR Genomics and Bioinformatics, 3(4), lqab115.