How create a db for NCBI BLASTN

[SDPA_Pet]

Hello, I have some metagenomic contigs and I want to use blastn against Silva SSU and LSU database to get taxa information.

I download the Silva RDP database from here in fasta format

http://www.arb-silva.de/documentation/release-111/

I try to use blastn to blast it directly. However, it doesn't work. Someone told me I have to convert it to NCBI format, but I don't know how to do it.

Also, the Silva database sequences are RNA seqs. I think I need to convert it to DNA first. I don't know how to do it.

I know after I convert it to DNA seqs, I can use "makeblastdb" to convert make the database. However, I don't know how to set "makeblastdb" parameters.

Can anyone help me. Post the scripts I should use.

Thanks,
Ben

[GenoMax]

See this page for the BLAST help: http://www.ncbi.nlm.nih.gov/books/NBK1763/. If you search for "makeblastdb" (you will need to find the 3rd or 4th occurrence) then you will see this command line example:

$ makeblastdb -in hs_chr –input_type blastdb -dbtype nucl -parse_seqids \
 -mask_data hs_chr_mask.asnb -out hs_chr -title \
 "Human Chromosome, Ref B37.1"

If you type

makeblastdb -help

in your terminal window you will be able to get detailed program options.

What OS are you using?

[mastal]

How create a db for NCBI BLASTN

Here is an example of the makeblastdb command,

$ makeblastdb -in hs_chr.fa -dbtype nucl -parse_seqids \
-out hs_chr -title "Human chromosomes, Ref B37.1"

taken from the 'Cookbook' section of the BLAST Command Line Applications User Manual

http://www.ncbi.nlm.nih.gov/books/NBK1763/

You may also want to look at some of the previous threads here on SEQanswers, for example,

http://seqanswers.com/forums/showthread.php?t=6498

Best wishes,
Maria

[SDPA_Pet]

I use windows7 blastn.

I try "$ makeblastdb -in hs_chr –input_type blastdb -dbtype nucl -parse_seqids
-mask_data hs_chr_mask.asnb -out hs_chr -title \
"Human Chromosome, Ref B37.1"

It didn't work. I need to convert Silva RDP fasta database to NCBI database.

I don't think I need a title. what is mask_data for.

I run this


D:\ME>makeblastdb -in LSURef_111_tax_silva.fasta -dbtype nucl -parse_seqids -out LSURef_111_tax_silva.ncbi.db


Building a new DB, current time: 04/04/2013 10:41:10
New DB name: LSURef_111_tax_silva.ncbi.db
New DB title: LSURef_111_tax_silva.fasta
Sequence type: Nucleotide
Keep Linkouts: T
Keep MBits: T
Maximum file size: 1000000000B
Adding sequences from FASTA; added 29306 sequences in 3.68226 seconds.

It looks successful, but I can't use the output file for blastn.

If anyone can leave your dropbox account for me, I can share my file to you.

So you can try it, you will know it won't work.

Here is the link that I download the fasta format database from Silva RDP

http://www.arb-silva.de/no_cache/download/archive/release_111/Exports/

LSURef_111_tax_silva.fasta.tgz is the file that I want to convert to NCBI format

Ben

[GenoMax]

It looks successful, but I can't use the output file for blastn.


Ben

What exactly is happening? Are you getting no results/error messages?

[SDPA_Pet]

What exactly is happening? Are you getting no results/error messages?

I run "makeblastdb -in LSURef_111_tax_silva.fasta -dbtype nucl -out LSURef_111_tax_silva.ncbi.db"

I have got three output files:

LSURef_111_tax_silva.ncbi.db.nhr
LSURef_111_tax_silva.ncbi.db.nin
LSURef_111_tax_silva.ncbi.db.nsq

I try all of them for blastn

Run:
blastn -query test.fna -db LSURef_111_tax_silva.ncbi.db.nhr -out out_test -evalue 1e-6

I got this

BLAST Database error: No alias or index file found for nucleotide database [LSURef_111_tax_silva.ncbi.db.nhr] in search path [D:\ME;;]

I don't know what happened.

Ben

[yzzhang]

you should run command
blastn -query test.fna -db LSURef_111_tax_silva.ncbi.db -out out_test -evalue 1e-6
try it to see if it works
Regards

[kmcarr]

Run:
blastn -query test.fna -db LSURef_111_tax_silva.ncbi.db.nhr -out out_test -evalue 1e-6

I got this

BLAST Database error: No alias or index file found for nucleotide database [LSURef_111_tax_silva.ncbi.db.nhr] in search path [D:\ME;;]

I don't know what happened.

Ben

Don't add ".nhr" to the name of your blastdb in the command, just use the base blastdb name, which in this case would be LSURef_111_tax_silva.ncbi.db

BLASTN will find the specific files it needs from the basename.

[SDPA_Pet]

you should run command
blastn -query test.fna -db LSURef_111_tax_silva.ncbi.db -out out_test -evalue 1e-6
try it to see if it works
Regards

The point is that I don't have this output "LSURef_111_tax_silva.ncbi.db"

I only got three output files:
LSURef_111_tax_silva.ncbi.db.nhr
LSURef_111_tax_silva.ncbi.db.nin
LSURef_111_tax_silva.ncbi.db.nsq

It looks I didn't convert my db correctly at the first step.

[kmcarr]

The point is that I don't have this output "LSURef_111_tax_silva.ncbi.db"

I only got three output files:
LSURef_111_tax_silva.ncbi.db.nhr
LSURef_111_tax_silva.ncbi.db.nin
LSURef_111_tax_silva.ncbi.db.nsq

It looks I didn't convert my db correctly at the first step.

The point is you aren't supposed to provide a full filename as the blastdb, only its base file name which in your case is "LSURef_111_tax_silva.ncbi.db". BLAST figures out the rest.

Trust us, we know what we're talking about.

[SDPA_Pet]

The point is you aren't supposed to provide a full filename as the blastdb, only its base file name which in your case is "LSURef_111_tax_silva.ncbi.db". BLAST figures out the rest.

Trust us, we know what we're talking about.

Thank you. You are right.

BTW, the parameters that I used are enough to create a good database file?

makeblastdb -in LSURef_111_tax_silva.fasta -dbtype nucl -out LSURef_111_tax_silva.ncbi.db

I just use "-dbtype nucl ". Anything else I should include?

Ben

[GenoMax]

BTW, the parameters that I used are enough to create a good database file?

Ben

If you did get output that makes sense then those parameters were adequate.

Did you manage to get the search to work?