To I.M. Larrinua:
Take heart! Other folks in our (Ron Davis') lab have also had persistent
problems with bacterial contamination when growing Arabidopsis seeds in liquid
culture. Although these were not from Lehle (and thus may suffer from a
different bug than yours), they solved the problem by including 250ug/ml
carbenicillin in the plant growth medium (as well as doing a conventional
surface sterilization beforehand). The seedlings didn't appear to be adversely
affected by its presence. Hope it works for you!