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F. Media for halophilic and specialised cultures
BG-11-MODBG-11 modifications for special applications
Variants of the basic medium tailored to particular experiments
- Application
- Synthetic biology, lipid accumulation, studies of nutrient limitation in Synechocystis and Synechococcus
- pH
- 7.5–8.0
- Source
- Composite practice based on Rippka et al., 1979
Composition
| Component | Amount per 1 L |
|---|---|
| Complete BG-11 composition | see section A |
| NaHCO₃ (C source without sparging) | 0.84–4.2 g (10–50 mM) |
| HEPES-NaOH pH 7.5 (buffer) | 2.38 g (10 mM) |
| Glucose (mixotrophy) | 1.0–5.0 g |
| Na₂S₂O₃·5H₂O (for agar only) | 0.3 g |
| A5 + Co trace element solution | 1.0 mL |
| Distilled water | to 1000 mL |
A5 + Co trace element solution
per 100 mL of solution · usage rate 1 mL per 1 L of medium (sufficient for 100 L) · storage at 4 °C in dark glass, 12 months
| Component | Weighed amount / volume |
|---|---|
| H₃BO₃ | 286 mg |
| MnCl₂·4H₂O | 181 mg |
| ZnSO₄·7H₂O | 22.2 mg |
| Na₂MoO₄·2H₂O | 39.0 mg |
| CuSO₄·5H₂O | 7.9 mg |
| Co(NO₃)₂·6H₂O | 4.94 mg (or 1 mL of a primary stock solution at 4.94 g/L) |
| Distilled water | to 100 mL |
Preparation
The basic BG-11 is prepared in the usual way (calcium last). The bicarbonate and HEPES are added before autoclaving; the glucose is sterilised separately by filtration and added to the cooled medium.
Notes
- Phosphorus-free BG-11 (BG-11 –P): omit K₂HPO₄; wash the inoculum twice by centrifugation. Used for studying polyphosphate granules.
- Sulfur-free BG-11 (BG-11 –S): replace MgSO₄·7H₂O with MgCl₂·6H₂O at 0.062 g/L (equimolar with respect to magnesium); replace the sulfates in the trace element solution with the corresponding chlorides.
- Glucose MUST NOT be autoclaved together with the medium: it undergoes the Maillard reaction with amino groups and forms products toxic to the cells; the medium turns brown.
- Na₂S₂O₃·5H₂O is added only to agar-solidified media — in liquid medium it is unnecessary and may inhibit growth.
- Dissolve the salts one at a time, in the order given; H₃BO₃ dissolves slowly — warming to 40 °C is permissible. Cobalt is added from a primary stock solution: a weighed amount of 4.94 mg cannot be measured on an ordinary balance. Primary Co stock solution: 494 mg Co(NO₃)₂·6H₂O in 100 mL of water, take 1 mL. Without cobalt the solution is simply called "A5". The appearance of a precipitate or turbidity indicates that the solution is no longer usable.