Download Microbial Reference Database

The Download Microbial Reference Database tool downloads selected references from GenBank and RefSeq, and outputs a single sequence list with all the necessary annotations for the taxonomic profiling (i.e., assembly IDs).

To run the tool, go to:

        Databases (Image databases_folder_closed_16_n_p) | Taxonomic Analyses | Download Microbial Reference Database

In the first window (figure 18.1), select the source of the database you wish to generate.

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Figure 18.1: Select the references you want to download.

You can choose to download a curated database. In this case, you can choose the full database, or one optimized to contain only contig with a length of at least 250,000 bp. Note that the two versions contain the same assemblies. The optimized small-size reference database is particularly useful for running the Taxonomic Profiling tool on a laptop computer.

If you select "Create custom reference database", then the section "Customize Database" will become active. Select one of the three options:

Click Next to select the source of the database you wish to generate (as in figure 18.2)

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Figure 18.2: Choose the type of reference you want for your custom database.

You can choose from:

You can also use other sources:

The time it will take to download the data (such as assembly summaries, genome report) depends on how many databases are downloaded and the bandwidth of your internet connection. No sequence data is downloaded at this point.

The tool will open a table called a Database builder (figure 18.3) from which you can design your own database. A series of functionality can help you filter and sort the table to extract the information relevant to your project.

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Figure 18.3: Output table from the Download Microbial Reference Database tool.

  1. Use the "Quick selection" button to quickly select predefined subsets for download:
    • Single scaffold complete genomes in RefSeq
    • Complete genomes in RefSeq
    • All complete genomes
    Each reference in the table will be labeled with one of the statuses listed here. In addition, some references are marked as representative genomes for a clade (repr) or as reference genomes (refr). We include references that are marked as Complete genome, Chromosome, representative genome and/or reference genome in these subsets.
  2. Aggregate the table to a specified taxonomic group using the drop down menu in the "Data" palette of the side panel. Use the category "Name" to de-aggregate the table.
  3. Use filter(s) to keep only the rows you are interested in, and click on the button "Include all" to create a database with the remaining rows.
  4. Alternatively, click on "Include all" rows first, set one or several filters, and use the button "Exclude all" on the remaining rows. Clear the filter(s) by clicking on the red buttons next to each filter set. The rows not filtered away in the second step should still be checked.

Once the table contains all desired rows, click Download selection. Close to the button, you can check how many references are selected, and an estimate of the total size of the selection.

The dialog shown in figure 18.4 allows you to choose to include or not all annotation tracks (note that these are not needed for taxonomic profiling applications), as well as to set an additional filter "Minimum contig length" (except if you have selected the curated database). It also warns about the memory and disk requirements that will be needed to later run the Taxonomic Profiling tool with the database you are about to download.

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Figure 18.4: The Download selection wizard.