title: Bloom Filter Trie: an alignment-free and reference-free data structure for pan-genome storage.
abstract: BACKGROUND
  High throughput sequencing technologies have become fast and cheap in the past years. As a result, large-scale projects started to sequence tens to several thousands of genomes per species, producing a high number of sequences sampled from each genome. Such a highly redundant collection of very similar sequences is called a pan-genome. It can be transformed into a set of sequences "colored" by the genomes to which they belong. A colored de Bruijn graph (C-DBG) extracts from the sequences all colored k-mers, strings of length k, and stores them in vertices.
  
  
  RESULTS
  In this paper, we present an alignment-free, reference-free and incremental data structure for storing a pan-genome as a C-DBG: the bloom filter trie (BFT). The data structure allows to store and compress a set of colored k-mers, and also to efficiently traverse the graph. Bloom filter trie was used to index and query different pangenome datasets. Compared to another state-of-the-art data structure, BFT was up to two times faster to build while using about the same amount of main memory. For querying k-mers, BFT was about 52-66 times faster while using about 5.5-14.3 times less memory.
  
  
  CONCLUSIONS
  We present a novel succinct data structure called the Bloom Filter Trie for indexing a pan-genome as a colored de Bruijn graph. The trie stores k-mers and their colors based on a new representation of vertices that compress and index shared substrings. Vertices use basic data structures for lightweight substrings storage as well as Bloom filters for efficient trie and graph traversals. Experimental results prove better performance compared to another state-of-the-art data structure.
  
  
  BACKGROUND
  https://www.github.com/GuillaumeHolley/BloomFilterTrie.
authors.affiliation: Genome Informatics, Faculty of Technology, Bielefeld University, Bielefeld, Germany ; Center for Biotechnology, Bielefeld University, Bielefeld, Germany ; International Research Training Group 1906, Bielefeld University, Bielefeld, Germany.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Holley
authors.affiliation: Genome Informatics, Faculty of Technology, Bielefeld University, Bielefeld, Germany ; Center for Biotechnology, Bielefeld University, Bielefeld, Germany ; International Research Training Group 1906, Bielefeld University, Bielefeld, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Wittler
authors.affiliation: Genome Informatics, Faculty of Technology, Bielefeld University, Bielefeld, Germany ; Center for Biotechnology, Bielefeld University, Bielefeld, Germany ; International Research Training Group 1906, Bielefeld University, Bielefeld, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Stoye
keywords: Bloom filter; Colored de bruijn graph; Compression; Index; Pan-genome; Population genomics; Similar genomes; Succinct data structure; Trie