MacConkey plates

MacConkey Agar Fisher 212122 (Difco)

to distinguish Lac+ and Lac- bacterial strains.

50 g/L

Total plates needed =~625

in 2 L flasks

flasks	Total vol (L)	max # plates
1	1.75	70
2	3.5	140
3	5.25	210
4	7	280
5	8.75	350
6	10.5	420
7	12.25	490
8	14	540

• 2-L flasks, each with:
  • 87.5 g MacConkey dry mix
  • 1.75 L distilled water
  • magnetic stir bar
• Stir to mix.
• Cover loosely with foil
• Pack Pour-Boy tubing in foil to go in same cycle if it's not already sterile
• Autoclave 55 min, liquid cycle
• Cool till handle-able on stir plate
• Dispense 25 mL per plate with Pour-Boy, stacking 10 tall.

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in 4 L flasks

• 4 L flasks, each with
  • 175 g MacConkey dry mix
  • 3.5 L distilled water
  • magnetic stir bar
• Stir to mix.
• Cover loosely with foil
• Pack Pour-Boy tubing in foil to go in same cycle if it's not already sterile
• Autoclave 75 min, liquid cycle
• Cool till handle-able on stir plate
• Dispense 25 mL per plate with Pour-Boy, stacking 10 tall

flasks	total vol (L)	max # plates
1	3.5	140
2	7	280
3	10.5	420
4	14	560