Unconfigured Ad

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • cyanoevo
    Member
    • Jan 2015
    • 16

    #1

    Blasting contigs against reference database

    Apologies if this has been covered elsewhere, couldn't find a satisfactory answer easily....

    The problem: I have hi-seq 2500 PE reads from a microbial culture that contain ONE cyanobacterial genome of interest and several contaminating genomes. My understanding is that by blasting against a local reference database containing only cyanobacterial genomes, I could bin my contigs by those which contain any cyanobacterial genes and those which do not.

    Further analysis of G-C content and tetranucleotide frequencies could then be used to eliminate chimeric contigs, leaving me with a draft genome.

    Could anybody point me in the direction of resources to help me write a BLAST algorithm do perform this task, maybe using BioPython (I have just started learning python)? I don't need long stretches of sequence to align, just the presence of a single gene with a good match in a whole contig would be enough to put it in the 'keep' pile.

    I'm new to bioinformatics and essentially teaching myself so any pointers much appreciated...

    Cheers
    Nathan
  • westerman
    Rick Westerman
    • Jun 2008
    • 1104

    #2
    Use a program like bowtie2 or bbduk to bin reads.

    Comment

    • cyanoevo
      Member
      • Jan 2015
      • 16

      #3
      Bowtie2 looks useful, certainly. However, wouldn't this only keep reads that mapped directly to the reference genome, losing some good reads from my genome of interest? I was going along the lines of assembling contigs first and searching within them for matches to the reference.

      Comment

      • GenoMax
        Senior Member
        • Feb 2008
        • 7142

        #4
        This is a classic case for using BBSplit (http://seqanswers.com/forums/showthread.php?t=41288). Use the cyanobacterial genome(s) as the reference and the reads will be binned automatically. If you need help with the actual command line let us know.

        Comment

        • cyanoevo
          Member
          • Jan 2015
          • 16

          #5
          BBsplit looks great, thanks! Can't believe I hadn't seen it before, will try it out.
          Cheers
          N

          Comment

          Latest Articles

          Collapse

          • SEQadmin2
            Multiomic Liquid Biopsy: What DNA/RNA Panels Reveal That DNA Alone Can’t
            by SEQadmin2



            Tumors contain complex mixtures of cell populations that evolve in response to treatment and host-specific factors. Tissue biopsies provide only static snapshots of a tumor’s state. But what if we could follow that evolution over time using a minimally invasive technique?

            Liquid biopsies can detect tumor-derived material circulating in the bloodstream, providing a way to study treatment response, detect emerging resistance, and discover new biomarkers. Circulating
            ...
            10-14-2026, 09:55 AM
          • SEQadmin2
            New Genomics Technologies Take Aim at Long-Standing Limits
            by SEQadmin2


            Researchers using sequencing and genomics tools often have to make trade-offs. They can choose between speed or scale, short reads or long-range information, or targeted panels or a view of the whole transcriptome. New technologies that have been released this year are built to address those tough choices.

            We asked six companies the same four questions to learn about their latest products. The new technologies bring a lot to the table, including rethinking sequencing
            ...
            09-28-2026, 10:25 AM

          ad_right_rmr

          Collapse

          News

          Collapse

          Topics Statistics Last Post
          Started by SEQadmin2, 10-15-2026, 10:52 AM
          0 responses
          31 views
          0 reactions
          Last Post SEQadmin2  
          Started by SEQadmin2, 10-14-2026, 05:39 AM
          0 responses
          38 views
          0 reactions
          Last Post SEQadmin2  
          Started by SEQadmin2, 10-13-2026, 09:56 AM
          0 responses
          31 views
          0 reactions
          Last Post SEQadmin2  
          Started by SEQadmin2, 10-09-2026, 11:14 AM
          0 responses
          29 views
          0 reactions
          Last Post SEQadmin2  
          Working...