Kraken - Very Good Application of Jellyfish and Minimizer

A number of good lightweight application are coming out taking advantage of fast, lock-free kmer counting of Jellyfish. Previously, we discussed about Sailfish, which could get good speed gain over RSEM in RNAseq applications.

DEseq and Sailfish Papers for RNAseq

Good C++ Development Practices in Sailfish Code

We also talked about the Minimer concept published by Jim Yorke in 2004, which has been finding many uses lately.

De Novo Assembly of Human Genome with Only 1.5 GB RAM

Wood and Salzberg published a new paper in Genome Biology for rapidly classifying metagenome sequences, where they use both of those concepts.

Kraken: Ultrafast Metagenomic Sequence Classification Using Exact Alignments

Kraken is an ultrafast and highly accurate program for assigning taxonomic labels to metagenomic DNA sequences. Previous programs designed for this task have been relatively slow and computationally expensive, forcing researchers to use faster abundance estimation programs, which only classify small subsets of metagenomic data. Using exact alignment of k-mers, Kraken achieves classification accuracy comparable to the fastest BLAST program. In its fastest mode, Kraken classifies 100 base pair reads at a rate of over 4.1 million reads per minute, 909 times faster than Megablast and 11 times faster than the abundance estimation program MetaPhlAn. Kraken is available at http://ccb.jhu.edu/software/kraken/.

Salzberg, as always, continues to do very creative work. Speaking of quality of Kraken, we are happy to rely on Nick Loman’s word on it.