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Best Practice To Find Human Contamination In Microbiome?

I have gut human microbiome data, I would like to filter out human sequences. What would be the best practice? I thought of megablasting the reads (454) against the human genome and removing 100% identities. Any ideas to make this better / shorter?

Thanks,

Iddo

metagenomics human

3 answers

BWA-SW if you really care about speed. Or ssaha2 or blat if you are more comfortable with traditional tools.

If you have shotgun metagenomic data, this sounds like a reasonable plan - though you could swap out megabalst for a different/faster aligner like BLAT, and allow some degree of mismatch for sequencing error. If you have have targeted metagenomic data (e.g. a 16S amplicon), then you could additionally impose a filter for contamination hits to be off-target (e.g. non-16S).

If BLASTN against the NCBI-NT is possible for the reads, you could also try to use CARMA3 to filter out human sequences...

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