Cookie- og privatlivspolitik      Dansk udgave   DANSK

L1 (L1-Si, L1-Si+NH4)

(Guillard & Hargraves 1993, Nina Lundholm pers. com.)

The L1-medium is a modification of the f/2 medium. The difference is a broader trace metal composition in L1. We use it as standard medium for marine diatoms. The L1-trace metal solution is used also in many other media.

Our L1-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. L1-20 = is based on 20 ‰ filtered seawater).

1. Stock solutions for major elements

NaNO3 7.5 g/100 mL
NaH2PO4•H2O 0.5 g/100 mL
Na2SiO3•9 H2O* 3.0 g/100 mL

* Na2SiO3 = di-Sodium-metasilicate.

2. Primary stock solutions for trace elements

MnCl2•4 H2O 18.0 g/100 mL
ZnSO4•7 H2O 2.2 g/100 mL
CoCl2•6 H2O 1.0 g/100 mL
CuSO4•5 H2O 0.245 g/100 mL
Na2MoO4•2 H2O 1.99 g/100 mL
H2SeO3 0.13 g/100 mL
NiSO4•6 H2O 0.27 g/100 mL
Na3VO4 0.184 g/100 mL
K2CrO4 0.194 g/100 mL

3. Trace metal working stock solution
1) Dissolve 4.36 g Na2EDTA • 2H2O and 3.15 g FeCl3 6 H2O in ca. 900 mL H2O in a 1000-mL volumetric flask.
2) Add 1 mL of each trace metal primary stock solution.
3) Bring to 1000 mL with H2O.
4) Autoclave

4. Vitamin stock solution

Biotin 0.01 g/100 mL
Cyanocobalamine (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 20 mg Thiamine HCl (Vitamin B1) in ca. 80 mL dH2O in a 100 mL volumetric flask.
2) Add 1 mL of the biotin primary stock solution.
3) Add 0.1 mL of the cyanocobalamin primary stock solution.
4) Fill with dH2O to 100 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 Na2SiO3•9 H2O stock solution. (For diatoms and silicoflagellates only. Otherwise leave out).
1.0 mL Trace metal working stock solution.
0.5 mL Vitamin working stock solution.
Autoclave medium

Add 1 mL 500 mM NH4Cl2 to L1-Si medium and autoclave.

60 PSU L1 medium based on artificial seawater. E.g. ca. 75 g Instant Ocean to 1L dH2O.

Add 1 mL 500 mM NH4Cl2 to L1-Si medium and autoclave.

Guillard, R.R.L. 1983. Culture of phytoplankton for feeding marine invertebrates. In: Culture of marine invertebrates. Selected readings. (Ed. by C.J. Berg Jr). pp. 108-132. Hutchinson Ross Publ. C.; Stroudsberg, Pensylvania.
Guillard, R.R.L. & Hargraves, P.E. 1993. Stichochrysis immobilis is a diatom, not a chrysophyte. Phycologia 32(3), 234-236.
Keller, M.D., Selvin, R.C., Claus, W. & Guillard, R.R.L. 1987. Media for the culture of oceanic ultraphytoplankton. J.Phycol. 23(4), 633-638.