text: user14425: I downloaded and extract blast nt.24 database, but when I run :
  blastn -task blastn-short -query consulta.fa -db nt.24 -out misalida.txt
  it says: mdb_env_open: No such file or directory
  and if a try with nt instead of nt.24 it says:
  BLAST Database error: Could not find volume or alias file (nt.00) referenced in alias file (/root/my-documents/blastdb/nt/nt
  So my question is :
  Do I have to download all nt.xx files?
  And : Will it show the organisms in the output result?
  
  user92: In general, yes, you do need to download and extract all (nt.00 - nt.46 as of now) of the nt portions in order to do a comprehensive BLAST against all of nt. The database has been split up for convenience (to make smaller individual files), so all are necessary to be comprehensive.
  Once you download all the pieces, you’ll want to use nt as the database parameter to blastn.
  blastn -task blastn-short -query consulta.fa -db nt -out misalida.txt
  As for the second question - this depends on how you run the BLAST. Each accession is associated with a taxid, which will map to its taxonomy. This can be mapped back to the organism, but you may need to do some interpretation in order to convert the BLAST hits to the proper organism - this depends highly on what kind of sequences you are aligning.
  
original_text: 14425: <p>I downloaded and extract blast nt.24 database, but when I run :</p>
  <p>blastn -task blastn-short -query consulta.fa -db <strong>nt.24</strong> -out misalida.txt</p>
  <p>it says: mdb_env_open: No such file or directory</p>
  <p>and if a try with nt instead of nt.24 it says:</p>
  <p>BLAST Database error: Could not find volume or alias file (nt.00) referenced in alias file (/root/my-documents/blastdb/nt/nt
  So my question is :</p>
  <p>Do I have to download all nt.xx files?</p>
  <p>And : Will it show the organisms in the output result?</p>
   92: <p>In general, yes, you do need to download and extract all (nt.00 - nt.46 as of now) of the nt portions in order to do a comprehensive BLAST against all of nt. The database has been split up for convenience (to make smaller individual files), so all are necessary to be comprehensive.</p>
  <p>Once you download all the pieces, you’ll want to use <code>nt</code> as the database parameter to blastn.</p>
  <p><code>blastn -task blastn-short -query consulta.fa -db nt -out misalida.txt</code></p>
  <p>As for the second question - this depends on how you run the BLAST. Each accession is associated with a taxid, which will map to its taxonomy. This can be mapped back to the organism, but you may need to do some interpretation in order to convert the BLAST hits to the proper organism - this depends highly on what kind of sequences you are aligning.</p>
  