Comparative genomics with succinct colored de Bruijn graphs

DNA technologies have evolved significantly in the past years enabling the sequencing of a large number of genomes in a short time. Nevertheless, the underlying problem of assembling sequence fragments is computationally hard and many technical factors and limitations complicate obtaining the complete sequence of a genome. Many genomes are left in a draft state, in which each chromosome is represented by a set of sequences with partial information on their relative order. Recently, some approaches have been proposed to compare draft genomes by comparing paths in de Bruijn graphs, which are constructed by many practical genome assemblers. In this article we describe in more detail a method for comparing genomes represented as succinct colored de Bruijn graphs directly and without resorting to sequence alignments, called \(\texttt {gcBB}\), that evaluates the entropy and expectation measures based on the Burrows-Wheeler Similarity Distribution. We also introduce an improved version of \(\texttt {gcBB}\), called \(\texttt {multi-gcBB}\), that improves the time and space performance considerably through the selection of different data structures. We have compared phylogenies of 12 Drosophila species obtained by other methods to those obtained with \(\texttt {gcBB}\), achieving promising results.