Effect of Catalase on Hydrogen Peroxide Penetration into
            <i>Pseudomonas aeruginosa</i>
            Biofilms

Stewart, Philip S.; Roe, Frank L.; Rayner, Joanna; Elkins, James G.; Lewandowski, Zbigniew; Ochsner, Urs A.; Hassett, Daniel J.

doi:10.1128/aem.66.2.836-838.2000

Cited by 164 publications

(120 citation statements)

References 18 publications

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“…In addition, P. aeruginosa is an obligate aerobe that may be exposed to endogenous oxidative stress due to the metabolism of O 2 . Several mechanisms have been proposed in the literature for the defence of P. aeruginosa against oxidative intermediates (Mathee et al, 1999;Hassett et al, 1999;Stewart et al, 2000;Valente et al, 2000). An efficient way to scavenge reactive oxygen intermediates, which is unique to P. aeruginosa, is the formation of the exopolysaccharide alginate.…”

Section: Introductionmentioning

confidence: 99%

Iron deficiency leads to inhibition of oxygen transfer and enhanced formation of virulence factors in cultures of Pseudomonas aeruginosa PAO1

2003

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Pseudomonas aeruginosa PAO1 was recently found to exhibit two remarkable physiological responses to oxidative stress: (1) a strong reduction in the efficiency of oxygen transfer from the gas phase into the liquid phase, thus causing oxygen limitation in the culture and (2) formation of a clear polysaccharide capsule on the cell surface. In this work, it has been shown that the iron concentration in the culture plays a crucial role in evoking these phenomena. The physiological responses of two P. aeruginosa PAO1 isolates (NCCB 2452 and ATCC 15692) were examined in growth media with varied iron concentrations. In a computer-controlled bioreactor cultivation system for controlled dissolved oxygen tension (pO 2 ), a strong correlation between the exhaustion of iron and the onset of oxygen limitation was observed. The oxygen transfer rate of the culture, characterized by the volumetric oxygen transfer coefficient, k L a, significantly decreased under iron-limited conditions. The formation of alginate and capsule was more strongly affected by iron concentration than by oxygen concentration. The reduction of the oxygen transfer rate and the subsequent oxygen limitation triggered by iron deficiency may represent a new and efficient way for P. aeruginosa PAO1 to adapt to growth conditions of iron limitation. Furthermore, the secretion of proteins into the culture medium was strongly enhanced by iron limitation. The formation of the virulence factor elastase and the iron chelators pyoverdine and pyochelin also significantly increased under iron-limited conditions. These results have implications for lung infection of cystic fibrosis patients by P. aeruginosa in view of the prevalence of iron limitation at the site of infection and the respiratory failure leading to death.

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Section: Introductionmentioning

confidence: 99%

Iron deficiency leads to inhibition of oxygen transfer and enhanced formation of virulence factors in cultures of Pseudomonas aeruginosa PAO1

2003

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“…Based on these results, we could speculate that 2-CP penetration depth was about 400 mm in the treated biofilm during the experiments. Limited penetration of inhibitors into biofilms has been widely observed in previous investigations (de Beer et al, 1994;Stewart et al, 2001Stewart et al, , 2000Xu et al, 1996). In those articles, the concentration profiles of hydrogen peroxide or chlorine in biofilms were directly measured with microelectrodes and limited penetration of the biocides into the biofilms was demonstrated.…”

Section: Discussionmentioning

confidence: 89%

“…For example, microelectrode measurements of chlorine concentrations in biofilms directly showed that chlorine concentrations in the biofilms were typically only 20% or less of those in the bulk liquid (de Beer et al, 1994). Furthermore, microelectrode measurements of hydrogen peroxide penetration into biofilms revealed retarded penetration of the inhibitors (Stewart et al, 2000). Reduction of concentrations and hence the inhibitory effects of inhibitors in biofilm results in protecting bacteria in the deeper parts of the biofilm.…”

Section: Introductionmentioning

confidence: 98%

“…It has been speculated that the reduced susceptibility of bacteria in biofilm is due to reduction of inhibitor penetration by the bacteria and extracellular polymeric substances, neutralization of inhibitors by biofilm constituents, and difference in the physiological state associated with lower growth rate (de Beer et al, 1994;Stewart et al, 2001Stewart et al, , 2000Xu et al, 1996). For example, microelectrode measurements of chlorine concentrations in biofilms directly showed that chlorine concentrations in the biofilms were typically only 20% or less of those in the bulk liquid (de Beer et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Use of microelectrodes to investigate the effects of 2‐chlorophenol on microbial activities in biofilms

Satoh

Sasaki

Nakamura

et al. 2005

Biotech & Bioengineering

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In order to assess the applicability of using microelectrodes as a tool for inhibition tests, temporal and spatial inhibitory effects of 2-chlorophenol (2-CP) on O 2 respiration and nitrification activities in municipal wastewater biofilms were investigated using microelectrodes for O 2 and NH 4 þ . The time-course microelectrode measurements demonstrated that 2-CP inhibited O 2 respiration and nitrification activities within 6-18 min. The microbial activities were inhibited only in the upper 400 mm of the biofilms by 2-CP, and the bacteria present in the deeper parts of the biofilms were still active, probably due to limited penetration of 2-CP. These results could reasonably explain the difference in inhibitory ratios of the O 2 respiration and nitrification activities in the biofilms. O 2 respiration activity was incompletely inhibited, which was attributed to the presence of O 2 respiration activities in the deeper parts of the biofilm. In contrast, nitrification activity was significantly inhibited because ammonia-oxidizing bacteria were present in the upper parts of the biofilm. These results indicate that the microelectrodes with a very quick response time and a high spatial resolution are useful tools to study temporal and spatial inhibitory effects of inhibitors on in situ microbial activities in biofilms. ß 2005 Wiley Periodicals, Inc.

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“…Cerca de 99% de todas as bactérias em ambiente natural estão em biofilmes (DALTON; MARCH, 1998) que consistem de microrganismos aderidos a uma superfície auxiliados por substâncias poliméricas extracelulares (COSTERTON et al, 1994;DENYER;GORMAN;SUSSMAN, 1993;STEWART et al, 2000). Outra definição estabelece que o biofilme é a agregação de células microbianas, crescendo e se multiplicando em uma superfície, sendo essa agregação, promovida por substâncias poliméricas extracelulares produzidas pelos próprios microrganismos (FLINT; BREMER; BROOKS, 1997).…”

Section: Introductionunclassified

Influência da velocidade de circulação do leite na adesão de Pseudomonas aeruginosa sobre aço inoxidável

Figueiredo

Andrade

Ozela

et al. 2009

Ciênc. Tecnol. Aliment.

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Effect of Catalase on Hydrogen Peroxide Penetration into Pseudomonas aeruginosa Biofilms

Cited by 164 publications

References 18 publications

Iron deficiency leads to inhibition of oxygen transfer and enhanced formation of virulence factors in cultures of Pseudomonas aeruginosa PAO1

Iron deficiency leads to inhibition of oxygen transfer and enhanced formation of virulence factors in cultures of Pseudomonas aeruginosa PAO1

Use of microelectrodes to investigate the effects of 2‐chlorophenol on microbial activities in biofilms

Influência da velocidade de circulação do leite na adesão de Pseudomonas aeruginosa sobre aço inoxidável

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