The long-term action of recommended (RC) and near-recommended concentrations of several commercial biocides (Lonzabac 12.100, Genamin CS302D, benzalkonium chloride and 2-phenoxyethanol) on cells of S. cerevisiae wild-type strain DTXII was described using plating tests while short-term effects were determined using the potentiometric fluorescent probe diS-C3(3) that detects both changes in membrane potential and impairment of membrane integrity. A 2-d plating of cells exposed to 0.5xRC of benzalkonium chloride and Genamin CS302D for 15 min showed a complete long-term cell killing, with 2-phenoxyethanol the killing was complete only at 2xRC and Lonzabac caused complete killing at RC but not at 0.5xRC. The diS-C3(3) fluorescence assay performed immediately after a 10-min biocide exposure revealed several concentration-dependent modes of action: Lonzabac at 0.5xRC caused a mere depolarization, higher concentrations causing gradually increasing cell damage; benzalkonium chloride and Genamin CS302D rapidly damaged the membrane of some cells and depolarized the rest whereas 2-phenoxyethanol, which had the lowest effect in the plating test, produced a concentration-dependent fraction of cells with impaired membranes. Cell staining slightly increased during the diS-C3(3) assay; addition of a protonophore showed that part of the remaining undamaged cells retained their membrane potential. Comparison of short-term and long-term data implies that membrane depolarization alone is not sufficient for complete long-term killing of yeast cells under the action of a biocide unless it is accompanied by perceptible impairment of membrane integrity. The results show that the diS-C3(3) fluorescence assay, which reflects the short-term effects of a biocide on cell membranes, can be successfully used to assess the microbicidal efficiency of biocides.

• MeSH
• Anti-Infective Agents pharmacology   MeSH
• Benzalkonium Compounds pharmacology   MeSH
• Cell Membrane drug effects   MeSH
• Ethylene Glycols pharmacology   MeSH
• Fluorescent Dyes metabolism   MeSH
• Spectrometry, Fluorescence MeSH
• Carbocyanines metabolism   MeSH
• Membrane Potentials drug effects   MeSH
• Microbial Sensitivity Tests methods   MeSH
• Cell Membrane Permeability drug effects   MeSH
• Saccharomyces cerevisiae drug effects   growth & development   MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 3,3'-dipropylthiacarbocyanine MeSH Browser
• Anti-Infective Agents MeSH
• Benzalkonium Compounds MeSH
• Ethylene Glycols MeSH
• Fluorescent Dyes MeSH
• Carbocyanines MeSH
• phenoxyethanol MeSH Browser

Evaluation of emission spectra of fluorescent probes used for the monitoring of membrane potential in microbial cells can be greatly facilitated by using synchronously excited spectroscopy (SES). This method permits the suppression of undesirable spectrum components (contributions due to scattered light or cell autofluorescence) and leads to considerable increase in monitored emission intensity and to narrowing of spectral peaks. It allows an efficient fractional decomposition of the probe fluorescence spectra into their free and bound dye fluorescence components. The usefulness of the method was tested by monitoring the accumulation of the fluorescent membrane potential probe diS-C3(3) in yeast cells, which serves as a qualitative measure of the membrane potential.

• MeSH
• Fluorescent Dyes metabolism   MeSH
• Spectrometry, Fluorescence methods   MeSH
• Carbocyanines metabolism   MeSH
• Membrane Potentials physiology   MeSH
• Saccharomyces cerevisiae physiology   MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 3,3'-dipropylthiacarbocyanine MeSH Browser
• Fluorescent Dyes MeSH
• Carbocyanines MeSH