As an initial guess for a recipe, I'll start with 1.5% agar since that's what we use to grow E. coli. Instead of LB, I plan to use nonfat dry milk powder (NDMp) from the grocery, given that yogurt cultures feed on milk.
The instructions for the NDMp is to mix 90 g into water to make 1L final volume.
I measured 500mL diH2O in a graduated cylinder then emptied it into a 1L beaker. Using a piece of tape, I marked the bottom of the water's meniscus in the beaker as 500mL. (I learned to never trust the graduations on a beaker. They are often inaccurate. This is a way to get a calibrated graduation.) Then empty the beaker.
Add roughly 200mL of distilled H2O to the beaker.
Weigh out 45g NDMp and add it to the beaker. I like to weigh by difference, as I think it is a more accurate technique.
Weigh out 7.5g agar powder and add it to the beaker.
Fill the beaker with distilled H2O up to the tape marking to make 500mL final volume.
Put stir bar into beaker.
Stir for 10 minutes with a top plate temperature of 80C.
Empty the contents into a 1L glass culture bottle.
Screw the cap on loosely, label the bottle as “Milk agar: 15g/L agar + 90g/L nonfat dry milk” and write your name and today's date.
Make sure the cap is on the bottle but loose, i.e. a full turn or so away from closed.
Autoclave for 1 hour at 121C and 15psig.
[Figure 1. (Insert photo of) Milk agar that separated into two layers: a brownish yellow translucent upper layer and a lower layer that looks like scambled egg whites.]
Unfortunately, looks like the agar separated into two distinct layers. I'm guessing this is the milk curdling.