498. MAGNETOSPIRILLUM MEDIUM

KH₂PO₄ 0.68 g

NaNO₃ 0.12 g

L(+)-Tartaric acid 0.37 g

Succinic acid 0.37 g

Na-acetate 0.05 g

Yeast extract 0.10 g

Modified Wolin's mineral solution (see above) 5.00 ml

Fe(III) quinate solution 0.01 M 2.0 ml

Sodium resazurin (0.1% w/v) 0.50 ml

Na-thioglycolate 0.05 g

Vitamin solution (see above) 1.0 ml

Distilled water 1000.0 ml

Dissolve ingredients (except thioglycolate and vitamins) in the order given and adjust pH to 6.75 with NaOH₂. Sparge medium with 100% N₂ gas for 30-45 min and dispense under the same gas atmosphere into anoxic Hungate-type tubes to 50% of their volume. Seal vials with screw caps and gas tight butyl rubber closures. Autoclave at 121°C for 15 min. Before inoculation add thioglycolate and vitamins from stock solutions prepared under 100% N₂ gas and filter-sterilized. Then add sterile air (with hypodermic syringe through the rubber closure) to a concentration of ca. 1% (v/v) O₂ in the vial (e.g., add 1 ml air to a Hungate-type tube of 16 ml total volume). Strongly reduced conditions will not support growth of microaerophilic Magnetospirillum species. Use as inoculum 10% (v/v). Incubate tubes with medium without agitation in an inclined position. During growth O2 will be consumed and the pH will increase. For cultivation of magnetic cells we recommend preparation of liquid medium, while semi-solid medium is more suitable for demonstration of microaerophilic band formation and storage.

Modified Wolin's mineral solution:

Nitrilotriacetic acid (NTA) 1.50 g

MgSO₄ x 7 H₂O 3.00 g

MnSO₄ x H₂O 0.50 g

NaCl 1.00 g

FeSO₄ x 7 H₂O 0.10 g

CoSO₄ x 7 H₂O 0.18 g

CaCl₂ x 2 H₂O 0.10 g

ZnSO₄ x 7 H₂O 0.18 g

CuSO₄ x 5 H₂O 0.01 g

AlK(SO₄)₂ x 12 H₂O 0.02 g

H₃BO₃ 0.01 g

Na₂MoO₄ x 2 H₂O 0.01 g

NiCl₂ x 6 H₂O 0.03 g

Na₂SeO₃ x 5 H₂O 0.30 mg

Na₂WO₄ x 2 H₂O 0.40 mg

Distilled water 1000.00 ml

First dissolve NTA and adjust pH to 6.5 with KOH, then add minerals. Adjust final to pH 7.0 with KOH.

Vitamin solution:

Vitamin B₁₂ 100.00 mg

p-Aminobenzoic acid 80.00 mg

D-(+)-biotin 20.00 mg

Nicotinic acid 200.00 mg

Calcium pantothenate 100.00 mg

Pyridoxine hydrochloride 300.00 mg

Thiamine-HCl × 2 H₂O 200.00 mg

Distilled water 1000.00 ml

Fe(III) quinate solution 0.01 M

FeCl₃ × 6 H₂O 4.50 g

Quinic acid 1.90 g

Distilled water 1000.00 ml

Sterilize by filtration under 100% N2 gas atmosphere.

Updated: 21.05.2026