Preparation of Grape-juice Agar plates

Reagent	Final concentration	Amount
Sugar	3% (w/v)	30 gm
Yeast	1.7% (w/v)	17 gm
Agar	2.5% (w/v)	25 gm
Methyl benzoic acid	0.025% (w/v)	0.25 gm
Propionic acid	0.5% (v/v)	5 mL
Orthophosphoric acid	0.1% (v/v)	1 mL
Grape juice	33% (v/v)	333 mL

Adjust final volume to 1 liter. Heat in a microwave oven to dissolve. Pour into plates when cooled to ∼50°C. Store the plates at 4°C for a week.