Problems with filter and trimming 16S data

Question

[bpvalderrama]

Hi everyone!

I 'm working with 16S data to filter for quality and trim prior to assign taxonomy to my reads. For that, I'm working with dada2 package for R.

I tried to look the quality profile of the reads using plotQualityProfile function. The output make me doubt. What should I do with these 2 forward reads? They look as high quality reads, but with a drastic drop in quality arround 75 bp.

To clarify, It is not the case for their respective reverse reads.

If you need the others qualityplots, either forward or reverse, tell me to hang it up

Thanks to you in advance!