See also
  closed_ref 
command
  Closed-reference OTU 
assignent
GG97 is my name for the default closed-reference database used by QIIME. It is a subset of the Greengenes database (DeSantis et al. 2006) clustered at 97% identity. The filename in QIIME is 97_otus.fasta. I am posting it here because to the best of my knowledge it is not directly available for download; the only way to get it is to install and run the QIIME virtual box.
Download gg97_v13.8.tar.gz (29Mb)
	
	License
It is not clear to me which license applies. It 
	is not included in the QIIME 
	github repository as far as I can tell. 
	According to the
	
	Greengenes download page (accessed 19 May 2017), the Greengenes Database
	by
	
	The Greengenes Database Consortium is licensed under a
	
	Creative Commons Attribution-ShareAlike 3.0 Unported License. However, 
	the version (13.8) in the QIIME virtual box is not available from the 
	Greengenes download page at the time of writing (the latest version there is 
	13.5). The QIIME source code is
	licensed 
	under GPL2.
	Reference
DeSantis, T.Z. et al., 2006. Greengenes, a chimera-checked 16S rRNA gene 
	database and workbench compatible with ARB. AEM 72(7), pp.5069-72.