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How to identify every read in a fastq file?

Hi, Everybody is looking for their target reads in a fastq file, and I am just sitting here and can not find a good program to identify the remaining (junk) reads. I am working on ancient DNA (currently horse) illumina reads, and I want to identify the exact organisms (possibly pathogens, human or other contamination, etc) of the remaining reads besides the horse sequences (approx 20-30% of the data contains horse DNA actually). So, can anyone recommend a good program for this task? Thanks in advance :)

genome next-gen blast

WOW, thanks for everybody, I see many valuable information here :)

4 answers

First you need to align your reads to the expected reference that it may be contaminated with using FastQ Screen Or DeconSeq, then below post to remove it

http://seqanswers.com/forums/showpost.php?p=109308&postcount=6

This would seem like a good use case for something like Kraken: https://ccb.jhu.edu/software/kraken/

But your ability to assign every read in your experiment to an organism of origin will depend entirely on the completeness of your database.

This might be worth trying: https://github.com/smangul1/rop, see paper: http://biorxiv.org/content/early/2016/05/13/053041

I think it is specialized in:

discover the source of all reads, which originate from complex RNA molecules, recombinant antibodies and microbial communities.

Yes, it is not meant for this application but might give some ideas.

There are some suggestions in these previous threads:

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