I am not sure what a protein data base (PDB) medium is. Fundamentally, you can adjust pH of a solution with a more concentrated acid, you simply need smaller volumes and the risk of over-titration is higher.

Engelbert Buxbaum Sir Sorry for Misunderstanding! PDB mean Potato Dextreose Broth medium.

I only said it half in joke, but the point I wanted to make is to be careful with abbreviations, especially those used only in a small subfield.