A book called Molecular Biological Methods for Bacillus called for plating Bacillus subtilis cells on LB-agar plates with the following components:
A general-purpose medium containing per litre:
Bacto-tryptone 10 g
Bacto-yeast extract 5 g
NaCl 10 g
1 M NaOH 1.0 ml
Autoclave (151b/in^2, 30 min). For LB agar plates solidify with 1.5% (w/v) agar; for LB overlay use 0.7% agar.
The first three components and their corresponding amounts are the same as what I normally work with, but I usually add distilled water for plating E. coli instead of NaOH. According to Wikipedia's entry on lysogeny broth, NaOH can be added to adjust LB's pH. But the protocol here mentions nothing of that sort. In other protocols of the book, at least it would say "adjust to pH -- with 10 M NaOH" or 1 M NaOH, etc. So if it is not to adjust the pH for the growth of Bacillus subtilis, what other purpose does NaOH do for the bacteria?
Also, I usually autoclave my LB or LB-agar for 2 hours instead of 30 minutes. Would autoclaving at 2 hours instead of 30 minutes affect NaOH?