Every feature in only 1 sample


I have sequencing data (300 bp) of V3-V4 region. I received this data from illumina through casava files means every zip file is already named with R1 and R2. I did not receive any barcode file from seq facility. I am not sure it is multiplexed or demultiplexed. I imported this data to qiime. The process was smooth and checked the read quality. AFter this, i used dada2 for denoising of only forward reads as i was facing problem with merging of both forward and reverse reads due to truncation length. After denoisng, i receive more than 900 features and 1 million frequencies. I was happy that i got good features as comapre to merged reads but then i checked that all the features belong to one sample.

I do not understand why it happens like this and how can i resolve this problem.

Hello Muhammad,

Did you search the forums for similar issues? I found this thread, which also shows each feature in one sample because the barcodes were included in the reads. Each ASV was contaminated with a per-sample barcode, resulting in per-sample ASVs.

Let us know if you have any questions about how to trim out barcodes from your reads.

This topic was automatically closed 31 days after the last reply. New replies are no longer allowed.