Strain modifications for Medium 71
3 distinct modifications were found.
Omit thiosulfate from the medium and add 10.00 g/l elemental sulfur as substrate. For sterilization place the sulfur in screw-capped tubes, add 1-2 drops of distilled water and incubate on 3 successive days for 3 h at 90-100°C in a water bath. Before use, aseptically layer the sulfur onto the surface of autoclaved liquid basal medium.
Replace thiosulfate with 5.00 g/l tetrathionate (K2S4O6) added from a stock solution sterilized by filtration.