K-minimum
(CCAP)
The K-min as specified by CCAP (for details see www.ccap.ac.uk/media/documents/Kmin.pdf) is a rather large modification of Keller's et al. (1987) K-medium. The recipe below uses L1 stock solutions (marked with asterisks) when possible.
Our K-min medium is based on 30 ‰ filtered seawater if nothing else is noted. Otherwise the figure following the letters indicates the salinity of the seawater used (e.g. K-min-20 = is based on 20 ‰ filtered seawater).
1. Stock solutions
| NaNO3* | 7.5 g/100 mL |
| NaH2PO4•H2O* | 0.5 g/100 mL |
| Na2SeO3•5H2O | 0.002 g/L |
2. Primary stock solutions for trace elements
| MnCl2•4H2O* | 18.0 g/100 mL |
| ZnSO4•7H2O* | 2.2 g/100 mL |
| CoCl2•6H2O* | 1.0 g/100 mL |
| Na2MoO4•2H2O | 0.6 g/100 mL |
3. Trace metal working stock solution
1) Dissolve 5 g Na2EDTA • 2H2O in ca. 900 mL H2O in a 1000-mL volumetric flask
2) Add 3.15 g FeCl3 • 6H2O
3) Add 1 mL of each trace metal primary stock solution
4) Bring to 1000 mL with H2O
4. Vitamin primary stock solutions
| Biotin* | 0.01 g/100 mL |
| Cyanocobalamin (B12)* | 0.1 g/100 mL |
Note: Vitamin B12 and Biotin are obtained in a crystalline form. When preparing the Vitamin B12 Stock Solution allow for approximately 11% water of crystallization (For each 1.0 mg of Vitamin B12 add 0.89 ml dH2O). When preparing the Biotin Stock Solution allow for approximately 4% water of crystallization (For each 1.0 mg of Biotin add 9.6 ml dH2O).
Keep the vitamin solutions frozen. Bottles of polyethylene are recommended for storage of vitamins.
5. Vitamin working stock solution
1) Dissolve 100 mg Thiamine HCl (Vitamin B1) in ca. 80 mL dH2O in a 100 mL volumetric flask
2) Add 5 mL of the biotin primary stock solution
3) Add 0.5 mL of the cyanocobalamin primary stock solution
4) Fill with dH2O to 1000 mL
The vitamin working stock solution is divided into to 10-mL lots in polyethylene vials and kept frozen until use.
6. Final preparation of L-medium
Add to 1 liter seawater:
1.0 mL NaNO3 stock solution
1.0 mL NaH2PO4 • H2O stock solution
1.0 mL Na2SeO3 • 5H2O stock solution
1.0 mL Trace metal working stock solution
1 mL Vitamin working stock solution
Autoclave medium
Note: We routinely add NaHCO3 and HCl for minimizing precipitation in the following order (see also Harrison & Berges 2005):
1.5 mL 0.5 M NaHCO3
1.5 mL 0.5 M HCl
Mix and add to 1 liter seawater
Then add:
1.0 mL NaNO3 stock solution
1.0 mL NaH2PO4 • H2O stock solution
1.0 mL Na2SeO3 • 5H2O stock solution
1.0 mL Trace metal working stock solution
0.5 mL Vitamin working stock solution
Autoclave medium and cool quickly after autoclaving
References
Keller D.K., Selvin R.C., Claus W. & Guillard R.R.L. 1987. Media for the culture of oceanic ultraphytoplankton. J. Phycol. 23, 633-638.
