is it possible, with the current version 2017.9, to collapse different sample's taxa-bar plot into a single column accordingly with a specific feature in the Metadata-File?
It would make it easier to visualize a taxa-related difference on homogeneous sample and the plot will be more clean
We have a method qiime feature-table group, which is built for exactly this situation (and others)! What you'll want to do is take the feature-table you are currently using in the taxa barplot, group it by some metadata column, and feed that resulting feature-table into the taxa barplot.
Let me know if you need more specific help using that method, but hopefully the documentation makes sense!