Application of High-Throughput Sequencing: Discovery of Informative SNPs to Subtype Bacillus anthracis

Abstract

Single Nucleotide Polymorphisms (SNPs) are the most common and abundant genetic variation found in the genome of any living species, from bacteria to humans. In bacterial genotyping, these evolutionarily stable point mutations represent important DNA markers that can be used to elucidate deep phylogenetic relationships among worldwide strains, but also to discriminate closely related strains. With the advent of next generation sequencing (NGS) technologies, affordable solutions are now available to get access to the complete genome sequence of an organism. Sequencing efforts of an increasing number of strains provide an unprecedented opportunity to create comprehensive species phylogenies. In this study, a comparative analysis of 161 genomes of Bacillus anthracis has being conducted to discover new informative SNPs that further resolves B. anthracis SNP-based phylogenetic tree. Nine previously unpublished SNPs that define major groups or sub-groups within the B. anthracis species were selected and developed into SNP discriminative assays. We report here a cost-effective high-resolution melting-based genotyping method for the screening of 27 canonical SNPs that includes these new diagnostic markers. The present assays are useful to rapidly assign an isolate to one sub-lineages or sub-groups and determine its phylogenetic placement on the B. anthracis substructure population.