I remember that thread. I have used stevia for many years now, so I don't know if it actually helped me heal or not - other than not using sugar!
To answer the other question - no, cyst forms of the bacteria are not the same as biofilms. Biofilms are colonies of bacteria that form a protective covering - a film - that protects them from any anti-infective action -whether from our own bodies or from medication.
Cyst forms of the bacteria is one of three forms the Lyme disease bacteria can go into. The three are spirochete, cell wall deficient and cyst. They are functions that each individual bacteria can (& do) accomplish on their own, as opposed to the biofilm which is a 'community' of bacteria.
I really like this chart that shows the three forms of the Lyme bacteria and a few of the basic differences in them:
www.lymebook.com/top10forms