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Analysis of bacteria contaminating ultrapure water in industrial systems.

ABSTRACT: Bacterial populations inhabiting ultrapure water (UPW) systems were investigated. The analyzed UPW systems included pilot scale, bench scale, and full size UPW plants employed in the semiconductor and other industries. Bacteria present in the polishing loop of the UPW systems were enumerated by both plate counts and epifluorescence microscopy. Assessment of bacterial presence in UPW by epifluorescence microscopy (cyanotolyl tetrazolium chloride [CTC] and DAPI [4',6'-diamidino-2-phenylindole] staining) showed significantly higher numbers (10 to 100 times more bacterial cells were detected) than that determined by plate counts. A considerable proportion of the bacteria present in UPW (50 to 90%) were cells that did not give a positive signal with CTC stain. Bacteria isolated from the UPW systems were mostly gram negative, and several groups seem to be indigenous for all of the UPW production systems studied. These included Ralstonia pickettii, Bradyrhizobium sp., Pseudomonas saccharophilia, and Stenotrophomonas strains. These bacteria constituted a significant part of the total number of isolated strains (>or=20%). Two sets of primers specific to R. pickettii and Bradyrhizobium sp. were designed and successfully used for the detection of the corresponding bacteria in the concentrated UPW samples. Unexpectedly, nifH gene sequences were found in Bradyrhizobium sp. and some P. saccharophilia strains isolated from UPW. The widespread use of nitrogen gas in UPW plants may be associated with the presence of nitrogen-fixing genes in these bacteria.

SUBMITTER: Kulakov LA

PROVIDER: S-EPMC123900 | biostudies-literature | 2002 Apr

REPOSITORIES: biostudies-literature

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Analysis of bacteria contaminating ultrapure water in industrial systems.

Kulakov Leonid A LA McAlister Morven B MB Ogden Kimberly L KL Larkin Michael J MJ O'Hanlon John F JF

Applied and environmental microbiology 20020401 4

Bacterial populations inhabiting ultrapure water (UPW) systems were investigated. The analyzed UPW systems included pilot scale, bench scale, and full size UPW plants employed in the semiconductor and other industries. Bacteria present in the polishing loop of the UPW systems were enumerated by both plate counts and epifluorescence microscopy. Assessment of bacterial presence in UPW by epifluorescence microscopy (cyanotolyl tetrazolium chloride [CTC] and DAPI [4',6'-diamidino-2-phenylindole] sta ...[more]

PMID: 11916667

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Project description:BackgroundPatients on standard dialysis, in particular those on high-flux and high-efficiency dialysis, are exposed to hundreds of liters of dialysis-water per week. The quality of dialysis-water is a factor responsible for inflammation in dialysis patients. Inflammation is a potent trigger of atherosclerosis and a pathogenetic factor in anemia, increasing mortality and morbidity in dialysis patients. Current systems for water treatment do not completely eliminate bacteria and endotoxins. This prospective study tested whether improved dialysis-water purity by an additional ultrafilter can reduce inflammation and ameliorate hemoglobin levels, with a consequent reduction in erythropoietin-stimulating agents (ESA).MethodsAn ultrafilter, composed of two serially positioned devices with polysulfone membranes of 2.0 and 1.0 m2, respectively, was positioned within the fluid pathway before the dialysis machine. Prevalent dialysis patients were assigned either to continue dialysis with conventional dialysis-water (control phase) or to initiate dialysis sessions with improved dialysis-water purity (study phase). After 6 months, patients were crossed over. Total study duration was 1 year. Routine chemistry, bacterial count, endotoxin levels in dialysis-water as well as blood levels of pro- and anti-inflammatory cytokines, human serum amyloid A, C-reactive protein and fraction 5 of complement were measured.ResultsThirty-two patients completed the study. Mean bacterial count was lower and endotoxin levels were absent in dialysis-water obtained with the ultrafilter. At the end of the study-phase, C-reactive protein and pro-inflammatory cytokines decreased while anti-inflammatory ones increased. Hemoglobin levels were improved with lower ESA doses.ConclusionsAn additional ultrafilter improved dialysis-water purity, reduced levels of inflammation markers, ameliorated hemoglobin concentration with reduced ESA doses. These results remain speculative but they may generate studies to assess whether improved dialysis-water quality with an ultrafilter can reduce inflammation and improve survival of dialysis patients.

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Analysis of bacteria contaminating ultrapure water in industrial systems.

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Analysis of bacteria contaminating ultrapure water in industrial systems.

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