NCBI: dowload all genomes obtained from soil/marine/host associated bacteria/organisms

Question

[dago]

Let's say I would like to download from NCBI all genomes obtained for marine bacterial (or soil or gut associated). I figured that e-utilities could work for me.

Now, to get the information concerning the environmental source I should check the biosample. So I would do something like:

esearch -db biosample -query "marine" | efetch -format tabular

1: Photobacterium sanguinicancer CAIM 1827T
Identifiers: BioSample: SAMN04252530; Sample name: CAIM1827T.1; SRA: SRS1159004
Organism: Photobacterium sanguinicancri
Attributes:
    /strain="CAIM 1827"
    /host="Maja brachydactyla"
    /isolation source="Hemolymph"
    /collection date="06-Dec-2005"
    /geographic location="Spain: Ria a Coruna"
    /sample type="Bacterium"
    /altitude="0 m"
    /biomaterial provider="Collection of Aquatic Important Microorganisms"
    /culture collection="not applicable"
    /environment biome="marine"
    /host tissue sampled="hemolymph"
    /identified by="Bruno Gomez-Gil"
    /latitude and longitude="43.21 N 8.2200 W"
    /specimen voucher="not applicable"
Description:
    Draft genome of Photobacterium sanguinicancer type strain CAIM 1827T
    Accession: SAMN04252530 ID: 4252530
.....

Now, I would like to either download this assemblies/SRA or to access them, and this is making me quite confused. As far as I can read, I could use efetch, to retrieve sequences. However, there seem to be not direct link between querying biosamples and accessing the data via e-utilities.

Is someone out there taht could illuminate me?

Answer 1

[Pierre Lindenbaum]

there seem to be not direct link between querying biosamples and accessing the data via e-utilities.

Is someone out there taht could illuminate me?

you have to call elink https://www.ncbi.nlm.nih.gov/books/NBK25499/#_chapter4_ELink_

$ wget -q -O - "https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=biosample&db=taxonomy&id=6350818"

https://eutils.ncbi.nlm.nih.gov/eutils/dtd/20101123/elink.dtd">
<eLinkResult>

  <LinkSet>
    <DbFrom>biosample</DbFrom>
    <IdList>
      <Id>6350818</Id>
    </IdList>
    <LinkSetDb>
      <DbTo>taxonomy</DbTo>
      <LinkName>biosample_taxonomy</LinkName>

        <Link>
                <Id>408172</Id>
            </Link>

    </LinkSetDb>
  </LinkSet>
</eLinkResult>

here biosample : 6350818 (is https://www.ncbi.nlm.nih.gov/biosample/?term=6350818 ) and the taxon is 408172 https://www.ncbi.nlm.nih.gov/taxonomy/?term=408172 "marine metagenome"

[dago]

Hi Pierre, thanks very much for the answer. So I looked into it and that's how far I got. Starting from a biosample I can get the link to the assembly for example:

esearch -db biosample -query "SAMN06971996" | elink -target assembly 
<ENTREZ_DIRECT>
  <Db>assembly</Db>
  <WebEnv>NCID_1_14264864_130.14.22.215_9001_1501173337_1595509801_0MetA0_S_MegaStore_F_1</WebEnv>
  <QueryKey>3</QueryKey>
  <Count>1</Count>
  <Step>2</Step>
</ENTREZ_DIRECT>

However, I still cannot figure out how to access the real sequence as efetch want work.

[Pierre Lindenbaum]

 ( (wget -q -O - "https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=biosample&term=SAMN06971996"  | xmllint --xpath '/eSearchResult/IdList/Id[1]/text()' - && echo)  | xargs -I '{}' wget -q -O-  "https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=biosample&db=taxonomy&id={}" | xmllint --xpath '/eLinkResult/LinkSet/LinkSetDb/Link/Id[1]/text()' - && echo ) | xargs -I '{}' wget -q -O-  "https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id={}" | xmllint --xpath  '/TaxaSet/Taxon/ScientificName/text()' -


Candidatus Pelagibacter sp. TMED142

[dago]

I guess you answers are too inscrutable for me to understand! :)

Answer 2

[Charles Plessy]

Once you have the name or identifiers of the species you want to download, have a look at the following discussion: C: Download All The Bacterial Genomes From Ncbi.