Microbial production of ultrafine-grained magnetite by fermentation processes at room temperature.
A method of producing magnetite nanoparticles was developed through culturing a microorganism designated Haejae-1, Shewanella sp., in the presence of glucose and akaganeite (beta-FeOOH). Haejae-1 isolated from inter-tidal flat sediments was able to produce copious amount of ultrafine magnetite via glucose fermentation extracellularly under anaerobic conditions at room temperature, allowing for easy production, separation, and recovery of the magnetite. TEM observation revealed aggregates of small crystals of ultrafine magnetite which ranged in size from about 2 to 4 nanometers. Magnetic property by SQUID analysis showed the magnetite nanoparticles demonstrate superparamagnetic behavior. As a result, the method of the present study can be used to produce magnetite efficiently using inexpensive means at room temperature. The magnetite is a mineral of a great commercial value in that it is useful, e.g., in magnetic recording devices, drug carriers, and as toner for plain paper copiers.
Roh
Yul
Y
Faculty of Earth Systems and Environmental Sciences, Chonnam National University, Gwangju 500-757, Korea.
Kim
Yumi
Y
Lee
Sanghoon
S
Jang
Heedong
H
Suh
Yongjae
Y