**%T %a %i  %t %s**    
1、物种ID 
2、accession 序列ID           
3、sequence title
4、描述
5、序列

上面的导出%i 应该是序列id 我们可以不用这个字段
%a %t %T %s

Download the taxdb archive

perl update_blastdb.pl taxdb

Install it in the BLASTDB directory

gunzip -cd taxdb.tar.gz | (cd $BLASTDB; tar xvf - )

The preformatted databases are broken into smaller volumes and therefore can be downloaded more readily with fewer errors
A convenient Perl script (update_blastdb.pl found in the bin directory of a locally installed blast+ package) is available to simplify the download of these preformatted databases
Preformatted database files remove the makeblastdb formatting steps, and saves valuable processing time and diskspace
Taxonomic information is encoded within the preformatted databases and can be used to limit the scope of a blast search, and sequence retrieval, and scientific name addition through the included taxdb files
Sequences in FASTA format can be generated easily from the preformatted databases using the blastdbcmd utility when needed

makeblastdb -in Ecoli.proteins.fas -dbtype prot

makeblastdb -in Ecoli.genome.fas -dbtype nucl

blastn -task blastn  -query Salmonella.genome.fas -db Ecoli.genome.fas -evalue 1e-20 -num_threads 4 -out blastn.txt

pdf ("my_dotplot.pdf")
plot (blastnData$Query_Start, blastnData$Hit_Start, cex = .25)
dev.off()
quit()

Redundant: no attempts made to reduce redundancy
Protein
nr (NCBI)
The nr protein database maintained by NCBI as a target for their BLAST search services is a composite of SwissProt, SwissProt updates, PIR, PDB. Entries with absolutely identical sequences have been merged.
SwissProt
SwissProt is maintained by Amos Bairoch at the University of Geneva. SwissProt is a highly-curated, highly-crossreferenced, non-redundant database. Unfortunately, the cost of this labor-intensive quality enhancement process is that not every sequence is in SwissProt. If you wish to look up information about a sequence, SwissProt is the first place to look.
Non-redundant: manual curation used to provide only one entry per protein product; variants are annotated in entry.
Highly-cross-referenced to other databases.
PIR
The Protein Identification Resource was originated by the late Margaret Dayhoff. It attempts to enjoy the advantages of a complete and a non-redundant database.
Non-redundant: PIR1 section contains only one entry per protein product.
Redundant: Complete database (PIR1+PIR2+PIR3) has many redundancies
PDB
The Protein Data Bank, maintained by Brookhaven National Laboratory (Long Island, New York, USA), contains all publically available solved protein structures. Searches against the pdb can be used to ask whether any known 3D structures are similar to your query protein.
Non-redundant: Only the "best" determination of a given structure is left in the database; however, multiple structures for one molecule may exist due to other components (i.e. one entry uncomplexed, one complexed).
OWL
Prot. Eng. 3:153
Non-redundant: Automatically generated from component databases (see reference for further info).
Protein Motifs
Prosite
Prosite is a database of protein motifs maintained by Amos Bairoch at the University of Geneva (NAR 19:2241, 1991). Each motif (defined by either a regular expression or a profile) is accompanied by a description of the motif and what is known about it's biology, as well as a listing of the true positive, false negative, and false positive SwissProt entries for the pattern.
BLOCKS
BLOCKS is a database developed by Steve Henikoff and colleagues. A block is a gap-free multiple alignment of sequences based on Prosite (Henikoff & Henikoff, NAR 19:6565 1991).

IMPORTANT: As of February 4, 2020, the BLAST databases on the FTP site are version 5 (v5).
At the same time, the databases offered has been changed. This document reflects those changes.
Information on newly enabled features with the v5 databases at
https://ftp.ncbi.nlm.nih.gov/blast/db/blastdbv5.pdf

This document describes the BLAST databases available on the NCBI FTP site under
the /blast/db directory. The direct URL is ftp://ftp.ncbi.nlm.nih.gov/blast/db

1. Quick Start

   • Get all numbered files for a database with the same base name:
     Each of these files represents a subset (volume) of that database,
     and all of them are needed to reconstitute the database.
   • After extraction, there is no need to concatenate the resulting files:
     Call the database with the base name, for nr database files, use "-db nr".
   • For easy download, use the update_blastdb.pl script from the blast+ package.
   • Incremental update is not available.

2. General Introduction

BLAST search pages under the Basic BLAST section of the NCBI BLAST home page
(http://blast.ncbi.nlm.nih.gov/) use a standard set of BLAST databases for
nucleotide, protein, and translated BLAST searches. These databases are made
available as compressed archives of pre-formatted form) and can be donwloaed from
the /db directory of the BLAST ftp site (ftp://ftp.ncbi.nlm.nih.gov/blast/db/).
The FASTA files reside under the /FASTA subdirectory.

The pre-formatted databases offer the following advantages:
* Pre-formatting removes the need to run makeblastdb;
* Species-level taxonomy ids are included for each database entry;
* Databases are broken into smaller-sized volumes and are therefore easier
to download;
* Sequences in FASTA format can be generated from the pre-formatted databases
by using the blastdbcmd utility;
* A convenient script (update_blastdb.pl) is available in the blast+ package
to download the pre-formatted databases.

Pre-formatted databases must be downloaded using the update_blastdb.pl script or
via FTP in binary mode. Documentation for this script can be obtained by running
the script without any arguments; Perl installation is required.

The compressed files downloaded must be inflated with gzip or other decompress
tools. The BLAST database files can then be extracted out of the resulting tar
file using the tar utility on Unix/Linux, or WinZip and StuffIt Expander on
Windows and Macintosh platforms, respectively.

Large databases are formatted in multiple one-gigabyte volumes, which are named
using the basename.##.tar.gz convention. All volumes with the same base name are
required. An alias file is provided to tie individual volumes together so that
the database can be called using the base name (without the .nal or .pal
extension). For example, to call the est database, simply use "-db est" option
in the command line (without the quotes).

For other genomic BLAST databases, please check the genomes ftp directory at:
ftp://ftp.ncbi.nlm.nih.gov/genomes/

3. Contents of the /blast/db/ directory

The pre-formatted BLAST databases are archived in this directory. The names of
these databases and their contents are listed below.

+-----------------------------+------------------------------------------------+
File Name | Content Description
+-----------------------------+------------------------------------------------+
README | README for this subdirectory (this file)
nr.tar.gz | Non-redundant protein sequences from GenPept,
Swissprot, PIR, PDF, PDB, and NCBI RefSeq
nt.tar.gz | Partially non-redundant nucleotide sequences from
all traditional divisions of GenBank, EMBL, and DDBJ
excluding GSS,STS, PAT, EST, HTG, and WGS.
landmark.tar.gz | Proteome of 27 model organisms, see
https://blast.ncbi.nlm.nih.gov/smartblast/smartBlast.cgi?CMD=Web&PAGE_TYPE=BlastDocs#searchSets
16S_ribosomal_RNA | 16S ribosomal RNA (Bacteria and Archaea type strains)
18S_fungal_sequences.tar.gz | 18S ribosomal RNA sequences (SSU) from Fungi type and reference material (BioProject PRJNA39195)
28S_fungal_sequences.tar.gz | 28S ribosomal RNA sequences (LSU) from Fungi type and reference material (BioProject PRJNA51803)
ITS_RefSeq_Fungi.tar.gz | Internal transcribed spacer region (ITS) from Fungi type and reference material (BioProject PRJNA177353)
ITS_eukaryote_sequences.tar.gz| Internal transcribed spacer region (ITS) for eukaryotic sequences
LSU_eukaryote_rRNA.tar.gz | Large subunit ribosomal RNA sequences for eukaryotic sequences
LSU_prokaryote_rRNA.tar.gz | Large subunit ribosomal RNA sequences for prokaryotic sequences
SSU_eukaryote_rRNA.tar.gz | Small subunit ribosomal RNA sequences for eukaryotic sequences
ref_euk_rep_genomestar.gz | Refseq Representative Eukaryotic genomes (1000+ organisms)
ref_prok_rep_genomestar.gz | Refseq Representative Prokaryotic genomes (5700+ organisms)
ref_viruses_rep_genomestar.gz | Refseq Representative Virus genomes (9000+ organisms)
ref_viroids_rep_genomestar.gz | Refseq Representative Viroid genomes (46 organisms)
refseq_protein.*tar.gz | NCBI protein reference sequences
refseq_rna.*tar.gz | NCBI Transcript reference sequences
swissprot.tar.gz | Swiss-Prot sequence database (last major update)
pataa.*tar.gz | Patent protein sequences
patnt.*tar.gz | Patent nucleotide sequences. Both patent databases
are directly from the USPTO, or from the EPO/JPO
via EMBL/DDBJ
pdbaa.*tar.gz | Sequences for the protein structure from the
Protein Data Bank
pdbnt.*tar.gz | Sequences for the nucleotide structure from the
Protein Data Bank. They are NOT the protein coding
sequences for the corresponding pdbaa entries.
taxdb.tar.gz | Additional taxonomy information for the databases
listed here providing common and scientific names
FASTA/ | Subdirectory for FASTA formatted sequences
v4/ | BLAST databases in version 4 (v4). These files are no
longer being updated.
cloud/ | Subdirectory of databases for BLAST AMI; see
http://1.usa.gov/TJAnEt
+-----------------------------+------------------------------------------------+

4. Contents of the /blast/db/FASTA directory

This directory contains FASTA formatted sequence files. The file names
and database contents are listed below. These files must be unpacked before
use. They are provided as a convenience for users needing these sets in
FASTA format. For use with BLAST, it is preferable to use the BLAST database
on the FTP site.

+-----------------------+-----------------------------------------------------+
|File Name | Content Description |
+-----------------------+-----------------------------------------------------+
nr.gz* | non-redundant protein sequence database with entries
from GenPept, Swissprot, PIR, PDF, PDB, and RefSeq
nt.gz* | nucleotide sequence database, with entries from all
traditional divisions of GenBank, EMBL, and DDBJ;
excluding bulk divisions (gss, sts, pat, est, htg)
and wgs entries. Partially non-redundant.
pdbaa.gz* | protein sequences from pdb protein structures
swissprot.gz* | swiss-prot database (last major release)
+-----------------------+---------------------------------------------------+
NOTE:
(1) For screening for vector contamination, use the UniVec database:
ftp://ftp.ncbi.nlm.nih.gov/pub/UniVec/

• marked files have pre-formatted counterparts.

5. Database updates

The BLAST databases are updated regularly. There is no established incremental
update scheme. We recommend downloading the complete databases regularly to
keep their content current.

6. Non-redundant defline syntax

The non-redundant databases are nr, nt and pataa. Identical sequences are
merged into one entry in these databases. To be merged two sequences must
have identical lengths and every residue at every position must be the
same. The FASTA deflines for the different entries that belong to one
record are separated by control-A characters invisible to most
programs. In the example below both entries Q57293.1 and AAB05030.1
have the same sequence, in every respect:

Q57293.1 RecName: Full=Fe(3+) ions import ATP-binding protein FbpC ^AAAB05030.1 afuC
[Actinobacillus pleuropneumoniae] ^AAAB17216.1 afuC [Actinobacillus pleuropneumoniae]
MNNDFLVLKNITKSFGKATVIDNLDLVIKRGTMVTLLGPSGCGKTTVLRLVAGLENPTSGQIFIDGEDVTKSSIQNRDIC
IVFQSYALFPHMSIGDNVGYGLRMQGVSNEERKQRVKEALELVDLAGFADRFVDQISGGQQQRVALARALVLKPKVLILD
EPLSNLDANLRRSMREKIRELQQRLGITSLYVTHDQTEAFAVSDEVIVMNKGTIMQKARQKIFIYDRILYSLRNFMGEST
ICDGNLNQGTVSIGDYRFPLHNAADFSVADGACLVGVRPEAIRLTATGETSQRCQIKSAVYMGNHWEIVANWNGKDVLIN
ANPDQFDPDATKAFIHFTEQGIFLLNKE

Individual sequences are now identifed simply by their accession.version.

For databases whose entries are not from official NCBI sequence databases,
such as Trace database, the gnl| convention is used. For custom databases,
this convention should be followed and the id for each sequence must be
unique, if one would like to take the advantage of indexed database,
which enables specific sequence retrieval using blastdbcmd program included
in the blast executable package. One should refer to documents
distributed in the standalone BLAST package for more details.

7. Formatting a FASTA file into a BLASTable database

FASTA files need to be formatted with makeblastdb before they can be used in local
blast search. For those from NCBI, the following makeblastdb commands are
recommended:

For nucleotide fasta file: makeblastdb -in input_db -dbtype nucl -parse_seqids
For protein fasta file: makeblastdb -in input_db -dbtype prot -parse_seqids

In general, if the database is available as BLAST database, it is better to use the
preformatted database.

8. Technical Support

Questions and comments on this document and NCBI BLAST related questions
should be sent to the blast-help group at:
blast-help@ncbi.nlm.nih.gov

For information about other NCBI resources/services, please send email to
NCBI User Service at:
info@ncbi.nlm.nih.gov

Non-curated databases (low quality):

GenBank/GenPept - unreviewed sequences submitted from individual laboratories and large-scale sequencing projects. Since these sequence records are owned by the original submitters and can not be altered, GenBank might contain many low quality sequences.
trEMBL - unreviewed section of UniProt. This section contains a computer-annotated supplement of SwissProt that contains all the translations of EMBL nucleotide sequence entries not yet integrated in SwissProt
Curated databases (high quality):

RefSeq - GenBank sequences that are manually curated by the NCBI staff. RefSeq records are owned by NCBI and can be updated as needed to maintain current annotation or to incorporate additional information.
SwissProt - manually annotated and reviewed protein sequences
PIR - non-redundant annotated protein sequence database
PDB - experimentally-determined structures of proteins, nucleic acids, and complex assemblies

https://www.biostars.org/p/164641/