Notes
This protocol outlines preparation preparation of Luria Broth (LB) and LB Agar for plates.
Source
Standard lab protocol
Materials
Luria Broth (LB)
- Bacto Tryptone.
- Bacto yeast extract.
- NaCl.
- Alternatively use pre-made LB/LBA mix. Use as recommended on the bottle (25g/L).
- Bacto Agar – Do check as agar for plants/algae culture is much more expensive.
- ddH2O
- NaOH – for buffering
Method
| LB Medium | 1 L | M |
|---|---|---|
| Bacto Tryptone | 10 g | – |
| Bacto Yeast Extract | 5 g | – |
| NaCl | 10 g | – |
| ddH2O | 850 mL | – |
| adjust pH to 7.0 with NaOH | fill to final volume with ddH2O | Autoclave before use. |
Luria Broth (LB)
- Prepare LB as above.
- Pour into appropriately sized Schott bottles. Recommend 500 mL in 1 L bottles.
- Autoclave on liquid cycle.
- LB can be stored at room temperature for several weeks before use.
Luria Broth (LB) Agar
- Add 7.5 g of Bacto agar per 500 mL of LB. Recommend 500 mL in 1 L bottles.
- Add a magnetic stir bar for mixing prior to pouring.
- Autoclave before use. This can be done with the initial preparation of LB, but often better to store LB, add agar and re-autoclave.
- Allow to cool to 60°C before pouring. Excessive heat makes it difficult to pour and can damage antibiotics. Use the magnetic stir plate to ensure it’s evenly mixed before pouring.
- Alternatively, !if no magnetic stir bar is included! LBA can be stored at room temperature for several weeks and re-melted by microwaving. 500 mL in 1 L bottles ensures no spills in case it bubbles over.
- Do not re-autoclave LBA.
