PathBacK (Pathways for Bacteria Knowledgebase) is an interactive, visual database containing more than 1500 bacterial metabolite pathways. Nearly 70% of these pathways (>1000) are not found in any other pathway database. PathBacK is designed specifically to support pathway elucidation and pathway discovery in microbiomics, metabolomics, transcriptomics, proteomics and systems biology. It is able to do so, in part, by providing exquisitely detailed, fully searchable, hyperlinked diagrams of bacterial metabolic and signaling pathways. All PathBacK pathways include information on the relevant bacterial Gram stain, subcellular locations, protein complex cofactors, protein complex locations, metabolite locations, chemical structures and protein complex quaternary structures. Each small molecule is hyperlinked to detailed descriptions contained in external databases like KEGG, PubChem, ChEBI, the HMDB or DrugBank and each protein complex or enzyme complex is hyperlinked to UniProt. All PathBacK pathways are accompanied with detailed descriptions and references, providing an overview of the pathway and processes depicted in each diagram. The database is easily browsed and supports full text, sequence and chemical structure searching. Users may query PathBacK with lists of metabolite names, genes/protein complex names, SwissProt IDs, GenBank IDs, taxonomy id or species names. These queries will produce lists of matching pathways and highlight the matching molecules on each of the pathway diagrams. All of PathBacK's images, image maps, descriptions and tables are downloadable.

The PathBacK interface is modeled after the interface used for PathBank and MiMeDB with a navigation bar for browsing, searching and downloading the database. On the navigation bar is a simple text query box that supports general text queries of the entire textual component of the database. PathBacK may be browsed by pathway, chemical compound, and protein complex. The pathway browse view generates a tabular synopsis of PathBacK's content with thumbnail images of the pathway diagrams, textual descriptions of the pathway, as well as lists of the corresponding chemical components and enzyme/protein complex components. This browse view allows users to casually scroll through the database, select different pathway categories or re-sort its contents. Clicking on a given thumbnail image or the PathBacK pathway button brings up a full-screen image for the corresponding pathway. Once opened the pathway image may be navigated using on the zoom and scroll buttons. As with most pathway databases, all of the chemical structures and protein_complexes/enzymes illustrated in PathBacK's diagrams are hyperlinked to other on-line databases or tables.