Toxic Effects of Ag(I) and Hg(II) onCandida albicansandC. maltosa: a Flow Cytometric Evaluation

Abstract

The effects of Ag(I) and Hg(II) on membrane potential and integrity of cells of Candida albicans and C. maltosa were determined with a flow cytometric procedure that employed an anionic membrane potentialsensitive dye, bis-(1,3-dibutylbarbituric acid) trimethine oxonol, and a membrane integrity indicator, propidium iodide. The membrane potentials of cells of both species were reduced rapidly within 15 min of exposure to Ag(I). No threshold dose for Hg(II) existed, and cells of both species lost membrane potential gradually in Hg(II) solutions. Cells of both species lost membrane integrity more rapidly in Ag(I) solutions than in Hg(II) solutions. In Ag(I) solutions, the decrease in the numbers of cells recoverable in culture occurred at a rate similar to the rate of cell depolarization and membrane permeabilization. In Hg(II) solutions, loss of cell recoverability preceded the loss of membrane potential and membrane integrity. C. albicans, in contrast to C. maltosa, showed no loss of membrane integrity after exposure to Hg(II) solutions for 1 h. Different rates of binding of Ag(I) and Hg(II) between the two species suggest that the two ions target different primary sites.

In vitro effects of Ag+ on planktonic and adhered cells of fluconazole-resistant and susceptible strains of Candida albicans, C. glabrata and C. krusei

“…This ''trailing'' phenomenon, which does not correlate with in vivo drug responses, may be related to differential tolerances via enhanced efflux activity of selected cells within the inoculum [38]. Our current flow cytometric data and that of earlier studies [11,29] suggests that number of cells with potential for tolerance appear to vary between strains and within the inocula with varied growth conditions. It is a general consensus that the Ag + is necessary for silver toxicity for microorganisms [13,21].…”

“…The lowest fluorescence intensity that included more than 99.9% of the cells in the live control was used as an analysis gate. The cells with fluorescence higher than the analysis gate were regarded as the permeabilized cells [29]. Table 3 Minimal biocidal concentrations of Ag + (mg/ml) for Candida spp.…”

“…Procedure for FCZ susceptibilities was adapted from those of Mateus et al [11] and those for silver were as described by Zhang and Crow [29]. Cell suspensions (1.0 Â 10 6 cells/ml) in MES and silicone sections with attached cells were exposed to 0-4.0 mg/ml Ag + in MES for 1 h at 22-24 1C.…”

Waste Engine Oil Degrading Potentials of Indigenous Fungi Isolated From Auto-Mechanic Workshops: Impacts of Heavy Metals (Zn and Pb) Co-Contamination and pH

“…A weight of each of these metal salts that gave a corresponding 1g of each of the respective metal was weighed and dissolved in 100 ml of sterile deionized water and agitated for 10 minutes to ensure complete dissolution and made up to 1 litre with sterile deionized water. Working concentrations of 1, 10, 100 and 1000 mgL -1 of the metals were prepared by serial dilutions of the stock solution [24] in sterile deionized water.…”

Mycogenic Formation of Silver Nanoparticles by the Azerbaijanese Environmental Isolate Candida macedoniensis BDU-MI44

“…It is known that many biological systems such as bacteria, fungi, yeast and molds, plants have been used for the convenient biosynthesis of metal nanoparticles. The use of microorganisms for synthesis of nanoparticles is potentially advantageous over plants due to the ease of scaling up the biohazards [6,7]. Yeasts are further easy to culture, maintain and due to considerable biomass favor the large scale production of a wide variety of metal nanoparticles including those of silver, gold, iron, cadmium, selenium, platinum and palladium [8,9,10].…”