Synthesis of Metal Oxide Microcapsules Using Metal-Reducing Bacteria

Abstract

Source: Lin, P., et al. Synthesizing Sodium Tungstate and Sodium Molybdate Microcapsules via Bacterial Mineral Excretion. J. Vis. Exp. (2018).

This video demonstrates the procedure for synthesizing rigid metal oxide microcapsules by culturing metal-reducing bacteria with metal ions, followed by sequential purification through sonication, centrifugation, and ethanol washing.

Protocol

CAUTION: Use latex gloves, protective eyeglasses, and a laboratory coat for performing the experiment. Whenever using the biosafety cabinet, turn on the cabinet fan and keep the cabinet door half-closed.

1. Preparation of Glass Beads

1. Place 100 glass beads of 3 mm diameter in a 100-mL laboratory bottle, and then cap it tightly.
2. Autoclave the contents at 120 °C for 10 min.
3. Leave the bottle to cool down to room temperature, then place it in the biosafety cabinet.

2. Preparation of Lysogeny Broth (LB)

1. Dissolve 8 g of powder of LB-Lennox broth in a 500-mL laboratory bottle with 400 mL of water.
2. Stir the conte....

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
LB(Lennox)broth with agar tablets	Sigma-Aldrich	L7075	1 tablet for 50 mL broth with agar
LB (Lennox) broth	Sigma-Aldrich	L3022-1KG	LB (Lennox) powder 1 kg
Dextrose anhydrous	Nihon Shiyaku Reagent	PL 78695	glucose
Sodium Tungstate	Nihon Shiyaku Reagent	PL 76050	Na2WO4 · 2H2O
Sodium Chloride	Nihon Shiyaku Reagent	PL 68131	NaCl
Ethanol 99.5%	Acros organics	AC615090040	CH3CH2OH
Water	Made in our university		de-ionlized water
Autoclave	Tomin Medical Equipmenco, Ltd., Taipei City, Taiwan, ROC	TM-329	heat to 120 °C for 10 min
Centrifuge	Digit System Laboratory System, New Taipei City, Taiwan, ROC	DSC302SD	centrifuge at 2025 x g
-80 °C Refrigerator	Panasonic	MDF-U3386S	Use to deep-freeze cryopreserve strain
Ultrasonic Homogenizer Sonicator Processor Cell Disruptor	Lenox	UPS-150	frequency 20 KHz power 150 W
Incubator	Customer made	custom made	heat to 40 °C or cool to 18 °C with time cotrol
Reciprocal shaking baths	Kingtech Scientific Co., Ltd	WBS-L
Digital Stirring Hot Plate	Corning	#6797-620D	use with PTFE magnetic stirring bar
Biosafety cabinet	Zong Yen co., LTD	ZYBH-420	All bacteria related process are done here
50 mL centrifudge tube	Falcon	14-432-22
15 mL centrifudge tube	Falcon	14-959-53A
Laboratory bottle 100 mL	Duran	21 801 24 5
Laboratory bottle 500 mL	Duran	21 801 44 5
Stainless steel spatula	Chemglass	CG-1981-10
PTFE Disposable Stir Bars	Fisher	S68066
Plastic Petri Dishes	Fisher	S33580A
Shewanella algae	Courtesy of author #3	Courtesy of author #3