Localization of enzymically enhanced heavy metal accumulation by Citrobacter sp. and metal accumulation in vitro by liposomes containing entrapped enzyme

Abstract

Growth of Pseudomonas aeruginosa ATCC 15692 was promoted when the strain was cultured in an iron-depleted succinate medium, supplemented with transferrin at 30%, 60% and 100% and lactoferrin at 60% and 100% ironsaturation. No significant differences between cell growth and pyoverdin production were observed when transferrin iron saturation was increased from 30% t o 100%; however, cell growth and pyoverdin production were strongly dependent on lactoferrin iron saturation. Lower lactoferrin iron saturation (< 30%) resulted in more pyoverdin production and reduced cell growth. Incubation of pyoverdin (19 pM) with 100 pM transferrin (So%, 60%and 100 YO iron-saturated) or lactoferrin (60 YO and 100% iron-saturated) led t o quenching of pyoverdin fluorescence. Also, 24 h incubation of pyoverdin (200 pM) with these two proteins (209 pM, 30%, 60% and 100% iron-saturated transferrin and 60% and 100% iron-saturated lactoferrin) at 25 "C resulted in increased absorbance at 460 nm. Both the fluorescence quenching and absorbance increases were iron-saturation-dependent. Taken together, these results support the conclusion that at physiological pH, P. aeruginosa pyoverdin can acquire iron from partially iron-saturated transferrin or lactoferrin.30602, USA

Pyoverdine secreted by Pseudomonas aeruginosa as a biological recognition element for the fluorescent detection of furazolidone

“…The highest fluorescence quenching efficiency of furazolidone was pH 7.2, whereas the maximum fluorescence intensity of pyoverdine at was pH 7.0. As a reversible pH indicator, the fluorescence of pyoverdines was strongly pH dependent, and the maximum fluorescence was also observed at pH 7.0 (Elliott, 1958;Xiao and Kisaalita, 1995). But for the binding of other substrates, especially for Fe 3+ , the neutral or slightly alkaline pH was optimal condition for the formation of stable complexes (Visca et al, 2007).…”

“…Supernatant was collected by centrifugation at 10,000g for 5 min at room temperature and filtered through membrane filter (pore size, 0.22 mm; Amicon). Pyoverdine in the supernatant was purified using Cu-sepharose (Xiao and Kisaalita, 1995). To prepare the Cu-sepharose, 5 ml Ni-sepharose was loaded in a syringe with a SPE cartridge (Bonna-Agela Technologies, Tianjin, China) on the bottom and was then washed with 5 ml buffer (0.02 M Na 2 HPO 4 , 0.5 M NaCl, and 0.05 M EDTA; pH 7.2).…”

“…Finally, the column was washed with elution buffer (0.02 M Na 2 HPO 4 and 1 M NH 4 Cl; pH 7.2), and fractions were collected "drop to drop" until the color of the effluent was not green. Then 0.1 mM EDTA was added in each fraction to recover the fluorescence (Xiao and Kisaalita, 1995). The fluorescence of each fraction was tested at emission and excitation wavelengths of 460 nm and 410 nm, respectively.…”

Pseudomonas aeruginosa Alkaline Protease Can Facilitate Siderophore-Mediated Iron-Uptake via the Proteolytic Cleavage of Transferrins

“…Moreover, a pyochelin-deficient mutant was able to grow in human sera, whereas a pyoverdin-deficient mutant exhibited severely retarded growth, and the addition of pyoverdin was found to restore the retarded growth of pyoverdin-deficient mutants in media containing transferrins. [4][5][6] P. aeruginosa produces several extracellular proteases. Of these, AprA and LasB have been extensively studied.…”

Regulation of Rab5 GTPase activity during Pseudomonas aeruginosa-macrophage interaction

“…Pseudomonas aeruginosa produces two major siderophores (pyochelin and pyoverdin) that bind iron efficiently (Xiao and Kisaalita 1997) and are then taken up by the bacteria through specific cell-surface receptors to support metabolic processes and control expression of other virulence factors (Meyer, Neely et al 1996;Vasil and Ochsner 1999;Takase, Nitanai et al 2000;Lamont, Beare et al 2002).…”