In this paper, we improve both the accuracy and speed of the Quikr approach to classifying a given set of metagenomic DNA sequences (16S rRNA). This is accomplished by increasing the number of "feature vectors" we use for each training genome, and by modifying the Lawson-Hanson algorithm for non-negative least squares.
Motivation: Estimation of bacterial community composition from a high-throughput sequenced sample is an important task in metagenomics applications. As the sample sequence data typically harbors reads of variable lengths and different levels of biological and technical noise, accurate statistical analysis of such data is challenging. Currently popular estimation methods are typically time-consuming in a desktop computing environment.
Results: Using sparsity enforcing methods from the general sparse signal processing field (such as compressed sensing), we derive a solution to the community composition estimation problem by a simultaneous assignment of all sample reads to a pre-processed reference database. A general statistical model based on kernel density estimation techniques is introduced for the assignment task, and the model solution is obtained using convex optimization tools. Further, we design a greedy algorithm solution for a fast solution. Our approach offers a reasonably fast community composition estimation method, which is shown to be more robust to input data variation than a recently introduced related method.
Availability and implementation: A platform-independent Julia implementation of the method is freely available at https://github.com/dkoslicki/SEK.