I am currently BLASTning against NCBI's NT database but I am considering also using WGS and ENV-NT. I was given the impression that WGS was populated by pulling from ENV-NT if the sequence was definitively classified to a specfific organism but after looking at the file sizes it seems the reverse. Could someone explain to me clearly the differences in NT, ENV-NT and WGS and maybe give an example of when I would and possibly wouldn't want to use specific databases or sets of databases?
Just assume whatever domain you are most familiar with and use those in your examples please.