Medium data

Search for medium no. = [1342].

Unless otherwise stated, sterilize media by autoclaving at 121°C for 15 min.

1342 MODIFIED RFENNIG MEDIUM WITH FERRIHYDRITE

NaCl	`2.0`	g
KH₂PO₄	`0.2`	g
NH₄Cl	`0.25`	g
MgCl₂·6H₂O	`0.5`	g
KCl	`0.4`	g
CaCl₂·2H₂O	`0.4`	g
Distilled water	`1.0`	L

Mix components thoroughly. Distribute the medium into culture vessels containing ferrihydrite slurry (see below, ca. 50 mM ferrihydrite) under a gas stream of CO₂, seal with butyl rubber stoppers and autoclave. After cooling, aseptically and anaerobically add per liter the following solutions (autoclaved or *filter-sterilized):

8% NaHCO₃ solution*	`50.0`	ml
1.0 M Sodium formate solution	`10.0`	ml
Trace vitamins* (see Medium No. 197)	`10.0`	ml
Trace element solution* (see Medium No. 899)	`1.0`	ml

Check pH to be 6.8-7.0.
Ferrihydrite slurry:
Slowly titrate 400 ml of 20 mM FeCl₃·6H₂O solution with 10% (w/v) NaOH to pH 7.0-7.5 with agitation on a magnetic stirrer. Wash the precipitate with distilled water three times. Remove the ferrihydrite suspension into a container, cover with water and store at room temperature overnight. Remove supernatant after centrifugation at 2000 rpm for 5 min. Distribute ferrihydrite slurry to culture vessels before pouring the medium described above (final frrihydrite concentration is approximately 50 mM in medium).