SVM (STANDARD VOLVOX MEDIUM: modified from Kirk’s SVM)

Starr's (1969) modification of Provasoli & Pintner's Medium, as further modified by Starr, Kochert and Kirk at various times.

For each 1000 ml of SVM required, stock solutions in the amounts indicated are added to ~950 ml of high-purity water (Milli-Q or triply-glass-distilled), pH is adjusted to 8.0 with NaOH, and volume is brought to 1000 ml. Dispense into desired tubes or flasks, autoclave and store in the cold.

All stocks except Biotin and B12 should be made fresh at least every 2 months. The P IV Metals should be made fresh every month, and sooner if there is any problem with the cultures that cannot be explained. Biotin and B12 stocks are kept frozen, the P IV metals solution is kept at room temperature in the dark, all other stocks are kept in the refrigerator.

*Biotin: make working stock from frozen stock of 2.5 mg/100 ml Biotin, by 1:10 dilution

**B12: make working stock from frozen stock of 15 mg/100 ml B12, by 1:100 dilution

Aliquot Biotin and B12 working stocks into Eppendorf tubes and store in the freezer.

***P IV Metal solution 2X

To 500 ml high-purity water that is being stirred, add 0.75 Gm Na2EDTA (EDTA will be 13.4 µM, final conc. in medium). After this has dissolved, add the following salts, in the order and amounts indicated, dissolving each before the next is added. (Wait 15 minutes after adding the FeCl3 before adding the MnCl2.)

(STORE P IV METALS IN DARK, AT ROOM TEMPERATURE; DO NOT REFRIGERATE)