681 PFENNIG'S MEDIUM
| K2HPO4 | 0.25 | g | 
| NH4Cl | 0.34 | g | 
| KCl | 0.34 | g | 
| MgSO4·7H2O | 0.5 | g | 
| CaCl2·2H2O | 0.25 | g | 
| Distilled water | 1.0 | L | 
| Trace element solution SL-10 (see Medium No. 433) | 0.5 | ml | 
| Na2S·9H2O | 0.3 | g | 
| NaHCO3 | 1.5 | g | 
| Vitamin B12 | 0.02 | mg | 
| Acetate (final concentration) | 2.0 | mM | 
| Thiosulfate (final concentration) | 10.0 | mM |