title: Destruction of Deinococcus geothermalis biofilm by photocatalytic ALD and sol-gel TiO2 surfaces.
abstract: The aim of the present work was to explore possibilities of photocatalytic TiO2 coating for reducing biofilms on non-living surfaces. The model organism, Deinococcus geothermalis, known to initiate growth of durable, colored biofilms on machine surfaces in the paper industry, was allowed to form biofilms on stainless steel, glass and TiO2 film coated glass or titanium. Field emission electron microscopy revealed that the cells in the biofilm formed at 45 degrees C under vigorous shaking were connected to the surface by means of numerous adhesion threads of 0.1-0.3 microm in length. Adjacent cells were connected to one another by threads of 0.5-1 microm in length. An ultrastructural analysis gave no indication for the involvement of amorphous extracellular materials (e.g., slime) in the biofilm. When biofilms on photocatalytic TiO2 surfaces, submerged in water, were exposed to 20 W h m(-2) of 360 nm light, both kinds of adhesion threads were completely destroyed and the D. geothermalis cells were extensively removed (from >10(7) down to below 10(6) cells cm(-2)). TiO2 films prepared by the sol-gel technique were slightly more effective than those prepared by the ALD technique. Doping of the TiO2 with sulfur did not enhance its biofilm-destroying capacity. The results show that photocatalytic TiO2 surfaces have potential as a self-cleaning technology for warm water using industries.
authors.affiliation: Department of Applied Chemistry and Microbiology, University of Helsinki, P. O. Box 56, 00014, Helsinki, Finland. mari.raulio@helsinki.fi
authors.forename: Mari
authors.initials: M
authors.lastname: Raulio
authors.forename: Viljami
authors.initials: V
authors.lastname: Pore
authors.forename: Sami
authors.initials: S
authors.lastname: Areva
authors.forename: Mikko
authors.initials: M
authors.lastname: Ritala
authors.forename: Markku
authors.initials: M
authors.lastname: Leskelä
authors.forename: Mika
authors.initials: M
authors.lastname: Lindén
authors.forename: Jarl B
authors.initials: JB
authors.lastname: Rosenholm
authors.forename: Kari
authors.initials: K
authors.lastname: Lounatmaa
authors.forename: Mirja
authors.initials: M
authors.lastname: Salkinoja-Salonen
mesh_terms: D018441:Biofilms / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D002384:Catalysis / Q000528:radiation effects; D034301:Deinococcus / Q000254:growth & development* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D010777:Photochemistry / Q000379:methods; D014025:Titanium / Q000494:pharmacology*
chemical_list: C009495:titanium dioxide; D014025:Titanium