MentaLiST -- The MLST pipeline developed by the PathOGiST research group
MLST (multi-locus sequence typing) is a classic technique for genotyping bacteria, widely applied for pathogen outbreak surveillance. Traditionally, MLST is based on identifying strain types from a set of a small number of housekeeping genes. With the increased availability of whole-genome sequencing (WGS) data, MLST methods have evolved toward larger typing schemes, based on a few hundred genes (core genome MLST, cgMLST) to a few thousand genes (whole genome MLST, wgMLST). Such large-scale MLST schemes have been shown to provide a finer resolution and are increasingly used in various contexts such as hospital outbreaks or foodborne pathogen outbreaks. This methodological shift raises new computational challenges, especially given the large size of the schemes involved. Very few available MLST callers are currently capable of dealing with large cgMLST and wgMLST schemes.
We introduce MentaLiST, a new MLST caller, based on a k-mer counting algorithm and written in the Julia language, specifically designed and implemented to handle large typing schemes. Tests on real and simulated data to show that MentaLiST is faster than any other available MLST caller while providing the same or better accuracy, and is capable of dealing with MLST schema with up to thousands of genes while requiring limited computational resources.
The easiest way of installing MentaLiST is by creating a new environment with Conda. To create a new conda environment that includes MentaLiST, run:
conda create -n mentalist -c bioconda mentalist
then activate it by running:
source activate mentalist
Once the mentalist conda environment is active, you should be able to run MentaLiST. Typing:
produces the help output.
The conda environment can be deactivated by running:
There is currently no conda recipe for julia on macOS, so a more manual installation process is required.
- Download the julia-0.6.2.dmg file from julialang.org and install it by dragging the
Julia-0.6.appbundle into your Applications folder.
- Launch the
Julia-0.6application and install all of the dependencies listed in the REQUIRE file:
julia> Pkg.update() julia> Pkg.add("Bio") julia> Pkg.add("OpenGene") julia> Pkg.add("Logging") julia> Pkg.add("ArgParse") julia> Pkg.add("Lumberjack") julia> Pkg.add("FastaIO") julia> Pkg.add("JLD") julia> Pkg.add("DataStructures")
- Clone the MentaLiST git repostory (https://github.com/WGS-TB/MentaLiST.git). MentaLiST can be run directly from the repository:
A notebook with basic commands to install MLST schema and running the allele calling algorithm can be found here.
You can also read more detailed instruction on how to deal with novel alleles.