observed feature is a straight line in the rarefaction curve

[Xio_Lee]

Hi Qiime2 community,

I have some nanopore 16S amplicon data (~1600bp). I have demultiplexed and removed the chimera outside the qiime2. I imported the data into qiime2 and used vsearch dereplicate and de novo cluster at 99%. The summary of the table and the rarefaction curve looked very funky to me. Seems to me that each sequence is one feature? and each sample is the same as the other.

I am not sure what is going on with this?

Thanks,
rarefaction-dn99.qzv (291.2 KB)

[thermokarst]

Hi @Xio_Lee, sorry for the slow reply here - someone will be with you as soon as possible. Thanks!

[lizgehret]

Hi @Xio_Lee,

Thanks for your patience here!

Could you summarize your FeatureData[Sequence] - produced by the dereplication step in q2-vsearch? This will help us to narrow down if the issue is being introduced within the OTU clustering, or from one of the upstream steps in this pipeline. Steps for this process can be found here, for reference.