Streptomyces features taxonomic classification

Hello there fellow :qiime2: users and devs!,

Yesterday I noticed that a portion of features (Sanger amplicons in this case) remained unclassified after classifying with primer-specific databases, GTDB r220 and SILVA 138, using either vsearch or NB. After a while, I added the classification coming from NCBI Refseq database (exact same methodology as the others) and noticed that Refseq classified the majority of unclassified features as Streptomyces sp, I then checked with Nucleotide database and BLAST and got mixed result, I checked SILVA (nothing to see there) and then I checked GTDB and many Streptomyces were undefined (or didn't reach certain quality I guess), see image below,

All this just let me wondering what's happening with the classification of Streptomyces and related taxa... I found this article ( and got even more flustered about this. So, questions are: Is there any suggestion in the community to classify features from this group accurately? or is it 16s non valid for now/anymore to classify individuals from this genus? anything in the middle?

Let me know what you think,
Luis Alfonso.

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Self update, same thing happens in a smaller scale in the metataxonomic data I have, GTDB classified 29 features as Streptomyces; SILVA, 35 and NCBI Refseq 44...

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