Strain-level sample characterisation using long reads and MAPQ scores

A simple but effective method for strain-level characterisation of microbial samples using long read data is presented. The method, which relies on having a non-redundant database of reference genomes, differentiates between strains within species and determines their relative abundance. It provides markedly better strain differentiation than that reported for the latest long read tools.

Good estimates of relative abundances of highly similar strains present at less than 1% are achievable with as little as 1Gb of reads. Host contamination can be removed without great loss of sample characterisation performance. The method is simple and highly flexible, allowing it to be used for various different purposes, and as an extension of other characterisation tools. A code body implementing the underlying method is freely available.