Effect of u.v. light irradiation, starvation and heat on Escherichia colibetabeta-D-galactosidase activity and other potential viability parameters

Fiksdal, Liv; Tryland, Ingun

doi:10.1046/j.1365-2672.1999.00796.x

Cited by 41 publications

(34 citation statements)

References 36 publications

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“…To eliminate false-positives requires determining how long it takes a dead cell's membrane to degrade sufficiently to allow uptake of propidium iodide. This time was determined by exposing cells to lethal doses of UV, a method that should not directly affect the cell membrane (16,45), and then following the change in viable cells over time.…”

Section: Resultsmentioning

confidence: 99%

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Viable but Nonculturable Bacteria Are Present in Mouse and Human Urine Specimens

et al. 2004

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The presence of viable but nonculturable bacteria in human clean-catch and mouse bladder-isolated urine specimens was investigated. Viable but nonculturable bacteria are alive but do not give rise to visible growth under nonselective growth conditions. Urine specimens obtained from human female volunteers with or without an active urinary tract infection were found to contain, on average, significantly more viable than culturable forms of bacteria. Additional support for the presence of viable but nonculturable cells in urine specimens considered sterile was obtained from examination of urine specimens obtained directly from the bladder of healthy mice. Because the viability assay used to study the viable but nonculturable condition is by necessity growth independent, and hence indirect, the accuracy of this assay that scores cells with intact cell membranes as being viable was studied. Greater than 95% of Escherichia coli cells exposed to lethal doses of UV irradiation were found to lose their membrane integrity within a day, a time frame similar to that used to examine urine specimens. These data suggest that viable but nonculturable cells can occur within regions of the urinary tract previously considered sterile.Urinary tract infections (UTIs) affect as many as 50% of women at least once during their lifetime (29, 32), and 25% of those who acquire a UTI will have another infection within the following 6 months (17). A UTI occurs when the urinary tract is infected with microorganisms, and uropathogenic Escherichia coli accounts for greater than 80% of all UTI cases (4, 30). One method of diagnosing a UTI is by culturing urine specimens; a threshold of 100,000 CFU/ml in clean-catch urine specimens is considered to indicate a UTI (4, 28). This threshold is not an absolute indicator, as both asymptomatic bacteriuria and patients with UTI symptoms having no culturable urine bacteria occur (29,32).Urine within the urinary tract is generally considered sterile (14). This conclusion is based upon a lack of culturable cells present in urine specimens obtained via clean-catch and catheterization methods. The presence of viable bacteria in the urine specimens of healthy patients would impact on hypotheses to explain recurrent UTIs as well as diagnostic procedures. Most recurrent UTIs result from reinfection; however, a higher percentage than would be expected by chance are caused by the index strain (6,18,26,27,41). The physical location and physiological status of index strain cells that remain after successful antibiotic therapy are unknown. Observations with a mouse model indicate that uropathogenic E. coli cells can remain in the urinary tract following antibiotic ther-

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Section: Resultsmentioning

confidence: 99%

“…Because UV light does not directly damage the cell membrane (16,45), uropathogenic E. coli cells were exposed to lethal doses of UV irradiation and then stored in the same manner as urine specimens. When cells were examined 24 h after exposure, 97% of the cells had been killed.…”

Section: Discussionmentioning

confidence: 99%

Viable but Nonculturable Bacteria Are Present in Mouse and Human Urine Specimens

et al. 2004

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“…Lack of correlation has been explained by enzyme activity from sources other than the culturable fecal indicator bacteria (E. coli, FC or total coliforms) that were used for comparison, for example, activity from non-fecal sources like algae and marine vibrios, non-specific cell-free enzymes or other cell-free substances capable of hydrolyzing the actual substrate, GAL-positive fecal microorganisms others than coliforms or by active, but non-culturable coliforms, and variations in the contribution from such sources [11,12,[23][24][25][26]. Disinfection or environmental stresses are shown to reduce the number of culturable fecal indicator bacteria more than the GAL activity, which may often explain why the enzyme activity is high even if the numbers of culturable coliforms are low [27][28][29][30].…”

Section: Discussionmentioning

confidence: 99%

Monitoring of β-d-Galactosidase Activity as a Surrogate Parameter for Rapid Detection of Sewage Contamination in Urban Recreational Water

Tryland

Braathen

Wennberg

et al. 2016

Water

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Simple, automated methods are required for rapid detection of wastewater contamination in urban recreational water. The activity of the enzyme β-D-galactosidase (GAL) can rapidly (<2 h) be measured by field instruments, or a fully automated instrument, and was evaluated as a potential surrogate parameter for estimating the level of fecal contamination in urban waters. The GAL-activity in rivers, affected by combined sewer overflows, increased significantly during heavy rainfall, and the increase in GAL-activity correlated well with the increase in fecal indicator bacteria. The GAL activity in human feces (n = 14) was high (mean activity 7ˆ10 7 ppb MU/hour) and stable (1 LOG 10 variation), while the numbers of Escherichia coli and intestinal enterococci varied by >5 LOG 10 . Furthermore, the GAL-activity per gram feces from birds, sheep and cattle was 2-3 LOG 10 lower than the activity from human feces, indicating that high GAL-activity in water may reflect human fecal pollution more than the total fecal pollution. The rapid method can only be used to quantify high levels of human fecal pollution, corresponding to about 0.1 mg human feces/liter (or 10 3 E. coli/100 mL), since below this limit GAL-activity from non-fecal environmental sources may interfere.

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“…Rhodamine 123 is a fluorogenic probe which reflect membrane potential. SYTOX green is a fluorescent nucleic acid stain that penetrates cells with compromised plasma membranes but will not cross the membranes of living cells with intact membranes (Fiksdal and Tryland, 1999). However all these methods fails to detect the UV-irradiation inflicted damage to bacterial cells.…”

Section: Identification Of Viability Of the Uv-irradiated Coliformmentioning

confidence: 99%

“…Because UV-irradiation does not directly affect the above mentioned cell functions. Till now, only one method was found to reflect the bacterial viability after UV-irradiation (Fiksdal and Tryland, 1999). This method, known as direct viable count (DVC) method involves enumeration of cells that are able to elongate in the presence of nalidixic acid and nutrients (Kogure et.…”

Section: Identification Of Viability Of the Uv-irradiated Coliformmentioning

confidence: 99%

Detecting the Viability of Particle Associated Bacteria After Uv-Radiation: A Molecular Biological Approach

Alam

Luxmy

Katayama

et al. 2003

J. of Wat. & Envir. Tech.

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Presence of wastewater particles is often cited as the reason for failure of UV-irradiation to inactivate targeted organisms to desired level. However, till now there is no method to directly assess the inactivation of particle-associated indicator organisms after UV-irradiation. In this study, we tried to establish a method to identify viable bacteria within wastewater particles. This method was then used to distinguish between particle-associated viable and non-viable bacteria after UV-irradiation. The objective was to assess the fraction of particles of different sizes that are associated with coliform bacteria and to analyze the impact that these particles may have on the residual coliform concentration after UV-radiation. We found that fluorescent in-situ hybridization (FISH) in conjugation with Direct viable count can be effectively used for identification and counting of particle associated Enterobacteriaceae. The method can also successfully distinguish viable bacteria after UV-radiation. We found that only 2 percent of the total coliforms in the supernatant from the secondary clarifier of the Shibaura water treatment plant is associated with particles. Association of coliforms were maximum for the particle size ranging from 41-µm to 80-µm. It was also found that UV-radiation can effectively penetrate through most of the waste water particles.

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Effect of u.v. light irradiation, starvation and heat on Escherichia colibetabeta-D-galactosidase activity and other potential viability parameters

Cited by 41 publications

References 36 publications

Viable but Nonculturable Bacteria Are Present in Mouse and Human Urine Specimens

Viable but Nonculturable Bacteria Are Present in Mouse and Human Urine Specimens

Monitoring of β-d-Galactosidase Activity as a Surrogate Parameter for Rapid Detection of Sewage Contamination in Urban Recreational Water

Detecting the Viability of Particle Associated Bacteria After Uv-Radiation: A Molecular Biological Approach

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