STEAMING MEDIA

Steaming re-melts agar media that has already been sterilized and has set solid in its bottle. It turns the agar back into a liquid so it can be poured into plates, without running a full autoclave cycle again.

WHAT YOU NEED?

• Bottles of sterile, solidified LB agar

• Steamer 

• Heat-resistant gloves

STEPS

1. Loosen the bottle caps slightly so pressure can escape.

2. Place the bottles in the steamer and heat for about 30 minutes, until the agar is completely liquid with no lumps.

3. Wearing heat-resistant gloves, swirl each bottle gently to check that it is fully melted.

4. Move the bottles to a tabletop to cool.

5. Once cooled, add any antibiotics and pour plates straight away.

TIPS

• Agar starts to set at around 40–45°C, so don’t let it cool too long before pouring.

• Swirl rather than shake, to avoid air bubbles.

• Don’t re-melt the same bottle over and over; repeated heating can darken the media.