I want to extract specific sequences and check their abundance in different samples/ know from which sample they originate.
I have 16S data, and I'm interested in just specific group of microorganisms. So, I would like to extract their sequences in order to create a phylogenetic tree, and be able to link the obtained results with samples metadata.
It sounds like you simply would like a means to filter / subset your data. You can do so by following the examples as outlined here. More specifically, this section.