Hitoshi Kunoh
Okayama University, Japan
Title: Novel functional materials created by mimicking Fe-oxidizing bacterium involved formation processes of iron oxides complex
Biography
Biography: Hitoshi Kunoh
Abstract
“Iron-oxidizing bacteria”, the genus Leptothrix or Gallionella, produce extracellular, uniquely-shaped microsheaths or fibrous bundles mainly composed of Fe oxides [named “BiogenousIron OXides (BIOX)”] ubiquitously in natural hydrosphere where groundwater outwells. Our microscopic and spectroscopic studies proved that BIOX was an ingenious hybrid of organic and inorganic materials produced through the interaction of bacterial exopolymers with aqueous-phase inorganics such as Fe, Si, P and often Ca. Intriguingly, BIOX was discovered to have a variety of the industrial functions: Lithium-ion battery anode material, catalyst enhancer, plant protectant and porcelain pigment. We have aimed to establish technology to create the novel functional materials for industrial application by mimicking the biogenic processes of BIOX formation. To date we succeeded to manipulate the texture and chemical components of the sheath-type BIOX by altering components of the culture medium for an isolated strain of Leptothrix sp. OUMS1 leading to creation of Si-rich Fe oxides complexes with diverse crystallinity, create Al-rich BIOX by culturing OUMS1 in media containing varied amounts of Al and create nano-scaled architectural acidic silica by heating naturally produced BIOX in a hydrogen gas flow followed by HCl treatment to remove Fe particles. Some of these novel materials were discovered to have great industrial potentials beyond artificially synthesized Fe oxides and naturally produced BIOX. We place our expectation on the eco-friendly, nontoxic, low-cost BIOX and related novel materials as fascinating functional materials for the next generation.
