Difco recommends filter sterilizing the nitrogen base, rather than autoclaving
it. I got mushy plates when I autoclaved it together with the agar and now
only filter sterilize it. I beleive the notion that the low pH in the media
hydrolyses the agar may have some merit. I beleive that yeast grows over a
fairly wide pH so the low pH of the original formulation may not be a necessity
but a mild selection against other organisms.
