Well, you could try out our really cool sequence curation plugin, RESCRIPt. You should be able to work through the tutorials linked there. It'll be a good starting point to see what you can do with sequence curation.
You can do just that! That is, you can assign taxonomy to
- your isolate database
- SILVA and/or GreenGenes (see the Data resources page)
- perhaps append your isolate sequences to the NCBI RefSeq db?
- any combination ...
Then you can pick the one that appears most reasonable to you, or you can run rescript merge-taxa
to return a taxonomy from all of the different approaches listed above, given certain parameters... One example use case is outlined here.