Cactus: A pipeline for identification and visualization of microbial interactions in metabolic pathways using shotgun metagenome sequences.
metagenomics, metabolic pathways,KEGG,Computational analysis.
Microorganisms are present throughout the biosphere. Their importance in the maintenance and recovery of various environments is known, but understanding how the various interactions occur at the metabolic level among microorganisms present in these habitats is still difficult. However, thanks to metagenomics and shotgun sequencing techniques, the studies on microbiota are growing and helping to solve this problem. Several tools have been developed to deal with the large amount of data generated and also help in the elucidation of doubts related to the participation of microorganisms in the metabolism of a microbiota, among the best known for this purpose are MG-RAST, IMG/M and MEGAN6. However, these tools, like many others, have a common characteristic in the analysis of metagenomic data, which is to split the result of the functional and taxonomic annotation, thus impairing the study of a particular microbiota. With this in mind, the overall goal was to develop a pipeline that could: I) treat the raw data, performing quality control and noise removal, as well as II) use the KEGG orthologue bank for functional annotation and consequently map the reads to their respective metabolic pathways, III) perform taxonomic annotation of the reads that were mapped to at least 1 metabolic pathway, and finally, IV) join the functional and taxonomic results, and through the use of the R language and libraries available in the Bioconductor project, create graphs that represent microbial interaction networks in metabolic pathways present in the KEGG database. To validate the tool, 3 metagenomes (represented in the study as X, Y and Z) were used, which have microorganisms widely used in the bioremediation of contaminated environments. The results of the tool were compared with the results of the MG-RAST application. As a result, a greater number of routes mapped by the Cactus application was seen, as well as the mapping of important metabolic routes in bioremediation, such as the metabolic route for biofilm formation.