title: Short-term inactivation rates of selected Gram-positive and Gram-negative bacteria attached to metal oxide mineral surfaces: role of solution and surface chemistry.
abstract: Metal oxides such as ferric or aluminum oxides can play an important role in the retention of bacteria in granular aquatic environments; however, their role in bacterial inactivation is not well understood. Herein, we examined the role of water chemistry and surface chemistry on the short-term inactivation rates of three bacteria when adhered to surfaces. To evaluate the role of water chemistry on the inactivation of attached bacteria, the loss in membrane integrity of bacteria attached to an iron oxide (Fe2O3) surface was measured over a range of water ionic strengths of either monovalent or divalent salts in the absence of a growth substrate. The influence of surface chemistry on the inactivation of attached bacteria was examined by measuring the loss in membrane integrity of cells attached to three surfaces (SiO2, Fe2O3, and Al2O3) at a specific water chemistry (10 mM KCl). Bacteria were allowed to attach onto the SiO2 or metal oxide coated slides mounted in a parallel-plate flow cell, and their inactivation rate (loss in membrane integrity) was measured directly without removing the cells from the surface and without disturbing the system. X-ray photoelectron spectroscopy analysis revealed a high correlation between the amounts of C-metal or O-metal bonds and the corresponding bacterial inactivation rates for each surface. Finally, for all three surfaces, a consistent increase in inactivation rate was observed with the type of bacterium in the order: Enterococcus faecalis, Escherichia coli O157:H7, and Escherichia coli D21f2.
authors.affiliation: Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 2B2, Canada.
authors.forename: Bahareh
authors.initials: B
authors.lastname: Asadishad
authors.forename: Subhasis
authors.initials: S
authors.lastname: Ghoshal
authors.forename: Nathalie
authors.initials: N
authors.lastname: Tufenkji
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D001422:Bacterial Adhesion / Q000502:physiology; D002462:Cell Membrane; D013293:Enterococcus faecalis / Q000502:physiology; D004926:Escherichia coli / Q000502:physiology; D019453:Escherichia coli O157 / Q000502:physiology; D005290:Ferric Compounds / Q000737:chemistry; D006090:Gram-Negative Bacteria / Q000472:pathogenicity / Q000502:physiology*; D006094:Gram-Positive Bacteria / Q000472:pathogenicity / Q000502:physiology*; D009994:Osmolar Concentration; D010087:Oxides / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry*; D014871:Water Microbiology
chemical_list: D005290:Ferric Compounds; D010087:Oxides; D014867:Water; C000499:ferric oxide; D012822:Silicon Dioxide; D000537:Aluminum Oxide