Yeast Extract for Friis Medium
- Yeast (93.75 g) + Super Q Water (562.5 ml) per flask
- Place in incubator at 37°C for 20 minutes.
- Heat to 90-100°C for 5 minutes
- Cool on ice.
- Pour into centrifuge bottles and centrifuge at 2500 rpms for 30 minutes (4°C).
- Filter supernatant through glass pads twice.
- Measure into bottles and label.
- Autoclave for 2-5 minutes at 115°C.
- Freeze in 45 and 90 ml aliquots.
125 g yeast per 750 ml water = 1 batch
Yield is approximately 700 ml.
Yeast extract preparation # 2
- Combine 929 ml Super Q water and 4.5 ml concentrated HCl in a 2 liter flask at room temperature.
- Slowly stir in 227 g Fleishman's dry yeast for baking. Mix well.
- Autoclave on liquid cycle three minutes.
- Cool on ice.
- Centrifuge at 8,000 rpm for 15 minutes. Save supernatants.
- Bring supernatant to pH 7.8 - 8.0.
- Filter supernatant through decreasing size filters (1.2 µm, 1.0 µm, 0.8 µm, 0.45 µm, 0.22 µm) using 142 mm filter holder and peristaltic punp.
- Filter sterilize through 0.22 µm filter bottle top filters. Alternatively, autoclave on liquid cycle for less fastidious species.
- Test for ability to support mycoplasma growth.
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