There's a lot of confusion being spread around--not to imply any
dishrespect for others, but if you had read the original message you would
know that the problem occurred only with dropout plates, and not with YPD
plates. This, it seems to me, eliminates the likelihood that glucose
carmelization was the problem.
I repeat my first message--I have found from unfortunate personal
experience that if the pH of dropout plates is not adjusted up, the plates
will be mush. There's a reason why amino acids are called acids. I don't
know how low you can go, but certainly pH 5.5 (or even 5.0) will gel just fine.
Of course, we all check the pH of our medium when we make it. Don't we?
lichten at helix.nih.gov