title: Photocatalytic bacterial inactivation by polyoxometalates.
abstract: The photocatalytic inactivation (PCI) of Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive) was performed using polyoxometalate (POM) as a homogeneous photocatalyst and compared with that of heterogeneous TiO2 photocatalyst. Aqueous suspensions of the microorganisms (10(7)-10(8)cfu ml(-1)) and POM (or TiO2) were irradiated with black light lamps. The POM-PCI was faster than (or comparable to) TiO2-PCI under the experimental conditions employed in this study. The relative efficiency of POM-PCI was species-dependent. Among three POMs (H(3)PW(12)O(40), H(3)PMo(12)O(40), and H(4)SiW(12)O(40)) tested in this study, the inactivation of E. coli was fastest with H(4)SiW(12)O(40) while that of B. subtilis was the most efficient with H(3)PW(12)O(40). Although the biocidal action of TiO2 photocatalyst has been commonly ascribed to the role of photogenerated reactive oxygen species such as hydroxyl radicals and superoxides, the cell death mechanism with POM seems to be different from TiO2-PCI. While TiO2 caused the cell membrane disruption, POM did not induce the cell lysis. When methanol was added to the POM solution, not only the PCI of E. coli was enhanced (contrary to the case of TiO2-PCI) but also the dark inactivation was observed. This was ascribed to the in situ production of formaldehyde from the oxidation of methanol. The interesting biocidal property of POM photocatalyst might be utilized as a potential disinfectant technology.
authors.affiliation: School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.
authors.forename: Eunyoung
authors.initials: E
authors.lastname: Bae
authors.forename: Jae Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Byeong Hee
authors.initials: BH
authors.lastname: Hwang
authors.forename: Jiman
authors.initials: J
authors.lastname: Yeo
authors.forename: Jeyong
authors.initials: J
authors.lastname: Yoon
authors.forename: Hyung Joon
authors.initials: HJ
authors.lastname: Cha
authors.forename: Wonyong
authors.initials: W
authors.lastname: Choi
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects; D002384:Catalysis / Q000528:radiation effects; D004926:Escherichia coli / Q000187:drug effects; D010777:Photochemistry / Q000379:methods*; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000633:toxicity; D014025:Titanium / Q000737:chemistry / Q000633:toxicity; D017973:Tungsten Compounds / Q000737:chemistry* / Q000633:toxicity*; D000099294:Polyoxometalates
chemical_list: D017382:Reactive Oxygen Species; D014025:Titanium; D017973:Tungsten Compounds; C102296:polyoxometalate I; D000099294:Polyoxometalates; C009495:titanium dioxide