title: Disruption of Autolysis in Bacillus subtilis using TiO2Nanoparticles.
abstract: In contrast to many nanotoxicity studies where nanoparticles (NPs) are observed to be toxic or reduce viable cells in a population of bacteria, we observed that increasing concentration of TiO2NPs increased the cell survival of Bacillus subtilis in autolysis-inducing buffer by 0.5 to 5 orders of magnitude over an 8 hour exposure. Molecular investigations revealed that TiO2NPs prevent or delay cell autolysis, an important survival and growth-regulating process in bacterial populations. Overall, the results suggest two potential mechanisms for the disruption of autolysis by TiO2NPs in a concentration dependent manner: (i) directly, through TiO2NP deposition on the cell wall, delaying the collapse of the protonmotive-force and preventing the onset of autolysis; and (ii) indirectly, through adsorption of autolysins on TiO2NP, limiting the activity of released autolysins and preventing further lytic activity. Enhanced darkfield microscopy coupled to hyperspectral analysis was used to map TiO2deposition on B. subtilis cell walls and released enzymes, supporting both mechanisms of autolysis interference. The disruption of autolysis in B. subtilis cultures by TiO2NPs suggests the mechanisms and kinetics of cell death may be influenced by nano-scale metal oxide materials, which are abundant in natural systems.
authors.affiliation: Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.|Center for the Environmental Implications of Nanotechnology (CEINT), Duke University, Durham, North Carolina, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: McGivney
authors.affiliation: Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.
authors.forename: Linchen
authors.initials: L
authors.lastname: Han
authors.affiliation: Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.|Center for the Environmental Implications of Nanotechnology (CEINT), Duke University, Durham, North Carolina, USA.
authors.forename: Astrid
authors.initials: A
authors.lastname: Avellan
authors.affiliation: Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.|Center for the Environmental Implications of Nanotechnology (CEINT), Duke University, Durham, North Carolina, USA.
authors.forename: Jeanne
authors.initials: J
authors.lastname: VanBriesen
authors.affiliation: Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.|Center for the Environmental Implications of Nanotechnology (CEINT), Duke University, Durham, North Carolina, USA.
authors.forename: Kelvin B
authors.initials: KB
authors.lastname: Gregory
mesh_terms: D000327:Adsorption; D001412:Bacillus subtilis / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D001433:Bacteriolysis / Q000187:drug effects*; D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D015169:Colony Count, Microbial; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D053768:Metal Nanoparticles / Q000737:chemistry*; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000378:metabolism*; D010457:Peptidoglycan / Q000737:chemistry / Q000378:metabolism; D018892:Proton-Motive Force / Q000187:drug effects*; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D010457:Peptidoglycan; C009495:titanium dioxide; D014025:Titanium; D009238:N-Acetylmuramoyl-L-alanine Amidase