Effect of extracellularly generated singlet oxygen on gram-positive and gram-negative bacteria.
In the separated surface-sensitizer system, a photosensitizer is physically separated from the substrate by a thin air layer under such conditions that only singlet oxygen can reach and oxidize the substrate, preventing the competition by type I photosensitized processes. This method has been used to study the reaction of singlet oxygen with Gram-positive (Streptococcus faecium) and Gram-negative (Escherichia coli) bacterial strains. Studies on cell samples exposed to singlet oxygen for different periods of time show a drastic decrease in survival for S. faecium, while E. coli becomes sensitive only when the integrity of the outer membrane is altered by treatment with CaCl2 or tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetic acid (Tris-EDTA). Biochemical and ultrastructural analyses suggest that the cytoplasmic membrane and the genetic material are the main sites damaged by singlet oxygen.
Valduga
G
G
Department of Biology, University of Padova, Italy.
Bertoloni
G
G
Reddi
E
E
Jori
G
G
D016984:Enterococcus faecium / Q000187:drug effects* / Q000528:radiation effects / Q000648:ultrastructure; D004926:Escherichia coli / Q000187:drug effects* / Q000528:radiation effects / Q000648:ultrastructure; D008027:Light; D008826:Microbial Sensitivity Tests; D008854:Microscopy, Electron; D010100:Oxygen / Q000633:toxicity*; D010777:Photochemistry; D026082:Singlet Oxygen
D026082:Singlet Oxygen; D010100:Oxygen