A. WET LAB PROTOCOLS

I.Recipes

I.a Agarose gel (50ml of 1% gel)

1. Weight 0.5 g of agarose
2. Dissolve in 50 ml of 1x TAE buffer
3. Microwave until completely dissolved
4. Cool down to ~50^oC (doesn't burn when you hold it in your hand)
5. Add 5ul of SybrSafe
6. Pour the gel into the casting stand
7. Cover the casting stand with foil to protect it from light (SybrSafe is sensitive to light)
8. Wait for the gel to solidify
9. Load the samples (5-10ul of sample + 1-2ul of Loading Dye)
10. Load 7-10ul of 2-log ladder
11. Run the gel at 110 V for ~45 min
12. Use lower gel percentage for larger samples (plasmids etc.) and higher gel percentage for smaller samples (~200-400 bp PCR products)

I.b. Buffers

I.b.1. 50X TAE Buffer (1 liter)
1. 242 g Tris-base
2. 18.61 g EDTA
3. 57.1 ml glacial acetic acid
4. Water top up to 1L

I.b.2. 1X TAE Buffer (1 liter)
1. Measure 20 ml of 50X TAE buffer
2. Add 980 ml dH2O

I.c. Growth media

I.c.1. Liquid Broth (LB) Medium – 250ml
1. The following ingredients have been added to a 250ml bottle:
- 2.5 g Tryptone
- 1.25 g Yeast Extract
- 2.5 g NaCl
- 250ml dH2O
2. Loose the lid of the bottle
3. Secure the lid with autoclave tape
4. Autoclave
5. Store the media at 4ᴼC (i.e. in the fridge)

I.c.2. LB agar (250 ml ~ 10 plates)
1. Add the following ingredients in a 250ml bottle:
- 2.5 g Tryptone
- 1.25 g Yeast Extract
- 2.5 g NaCl
- 3.75 g agar
- 250ml dH2O
2. Loose the lid of the bottle
3. Secure the lid with autoclave tape
4. Autoclave
5. Pour plates next to a Bunsen burner (if add antibiotics to the LB agar, antibiotics should be added only when the temperature of the flask becomes below 60ᴼC)
6. Wrap plates in foil and store them at 4ᴼC (i.e. in the fridge)

I.c.3. Chrome azurol (CAS) plates agar
CAS agar was prepared with a mixture of 90 ml Y minimal agar and 10 ml CAS mix which were prepared and autoclaved separately (Schwyn and Neilands, 1987). Following cooling to ~45 °C, the mixtures were mixed slowly ( with a pipette) and swirled until homogenous.
Y minimal agar
1.The agar was prepared by dissolving the following ingredients in 50 ml pure water:
- 0.169 g of sodium glutamate (Sigma)
- 0.3 g Tris base (Fisher Scientific)
- 0.1 ml of MgSO4.7H20 (10 % w/v)
- 0.1 ml of CaCl2.6H2O (22 % w/v)
- 0.1 ml of K2HPO4.3H2O (22 % w/v)
2. pH was adjusted to 6.8
3. 1.5 g agar was then added to the medium and autoclaved
CAS mix
For preparation of 100 ml CAS mix, 10 ml of 1 mM FeCl₃.6H2O (dissolved in 10 mM HCl) and 60.5 mg of CAS powder were dissolved in 50 ml of pure water giving a final volume of 60 ml. 72.9 mg of hexadecyltrimethylammonium bromide (HDTMA) was dissolved in 40 ml pure water and both solutions were mixed with constant stirring giving a total of 100 ml CAS mix solution. This dark purple solution was autoclaved and stored at room temperature in the dark. Mixing 10 μl of this solution with 90 μl Y minimal agar would give a final concentration of 10 μM FeCl₃. To prepare a high iron solution, 10 ml of 6 mM FeCl₃.6H2O (dissolved in 10 mM HCl) was used making a 60 μM FeCl₃ deep blue CAS mix solution.

I.c.6. SOC medium (200ml)
1. Add 1g yeast extract
2. Add 4 g tryptone
3. Add 2ml of 1M NaCl
4. Add 0.4ml of 1M KCl
5. Add 4ml of 0.5M Mg SO₄
6. Add 2ml of 1M MgCl²
7. Top up with dH2O -up to 200ml
Adjust the pH to 7.5
8. Autoclave+ cool down
9. Add 4ml of 20% glucose solution

I.c.7. M9 + agar
1. Add 180ml dH2O
2. Add 20 ml M9 salts
3. Add 3g agar
4. Autoclave samples + cool down
5. Add 0.4 ml 1M MgSO⁴
6. Add 0.4 ml 100mM CaCl²
7. Add 2 ml 50% glucose
8. Add 0.1 ml thiamine (1% stock)
9. Add 0.2 ml chloramphenicol (50mg/ml)
10. Pour plates

I.c.8. Defined medium
Autoclavable ingredients:
-MOPS-8.3625g
-Tricine-0.7125g
-NH₄Cl-0.5g
-K₂SO₄-550µl (0.5M stock solution)
-CaCl₂-5µl (100mM stock solution)
-MgCl₂-525µl (1M stock solution)
-NaCl-5ml (1M stock solution)
-K₂HPO₄-2.6375ml (0.5 M stock solution)
-Casamino Acids-2g
-Trace metals-1ml (1000x stock solution)
-Distilled Water-981ml
Optional ingredients:
-FeCl3 600µl (10mM stock solution)
Non-autoclavable ingredients:
-Sterile Glucose 8ml (25% solution)
-Sterile Thiamine 1ml (1% solution)