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Browsing by Author "Ijzerman, M. Marian"

Now showing 1 - 4 of 4
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    Development and evaluation of a colorimetric coliphage assay detection system
    Ijzerman, M. Marian; Hagedorn, Charles III; Reneau, Raymond B. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1994-03)
    A colorimetric coliphage assay detection system (CCADS), composed of a liquid colorimetric presence-absence (LCPA) method and a colorimetric agar-based (CAB) method, was developed to overcome the limitations imposed by the Standard Methods for the Examination of Water and Wastewater agar-based coli phage method (APHA method). Both CCADS methods are based on the induction of p-galactosidase in Escherichia coli and the release of the enzyme through a lytic cell infection. The released enzyme then cleaves a chromogenic substrate, which produces a colored reaction product. The CCADS was evaluated against the APHA method under laboratory conditions using a common sewage coliphage strain as a model (American Type Culture Collection-13706-B2), and under field conditions using water samples collected from four different sources. During thelaboratory evaluation, both the LCPA and CAB methods were found to be superior to the APHA method in coliphage detection because: 1) the LCPA and CAB methods were easier to read and interpret than the APHA method, 2) the LCPA and CAB methods were not subject to false positive results, 3) the ·LCPA method theoretically detected fewer coliphage particles than the APHA method, and 4) the CAB method detected roughly twice the number of coliphage particles detected with the APHA method. During the field evaluation, the results indicated: 1) the LCPA method was as reliable as either the CAB or APHA method in coliphage detection; 2) the LCPA and CAB methods were easier to read and interpret than the APHA method; 3) neither the LCPA method nor the CAB method were subject to false positive results; 4) the CAB method detected more coliphages than the APHA method under conditions of high fecal pollution, but both methods performed equally well in coliphage detection under conditions of low fecal contamination; and 5) the LCPA and CAB methods were equally as sensitive in coliphage detection as the APHA method. Finally, the coliphage group proved to be a useful indicator of fecal pollution in nonpotable water supplies exhibiting a high degree of fecal pollution, whereas they were not shown to be useful indicators in potable water supplies exhibiting low levels of fecal contamination. The lack of coliphage detection sensitivity under conditions of low fecal contamination does not appear to be method-limited, but the result of inefficiencies in processing environmental samples using the concentration methods currently available.
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    Development and evaluation of a colorimetric coliphage assay detection system
    Ijzerman, M. Marian (Virginia Tech, 1993-07-14)
    A Colorimetric Coliphage Assay Detection System (CCADS) that is composed of a Liquid Colorimetric Presence-Absence (LCPA) method and a Colorimetric Agar-Based (CAB) method was developed to overcome the limitations imposed by the Standard Methods for the Examination of Water and Wastewater agar-based coliphage method (APHA method). Both CCADS methods are based on the induction of β-galactosidase in Escherichia coli and the release of the enzyme through a lytic cell infection. The released enzyme then cleaves a chromogenic substrate which produces a colored reaction product. The CCADS was evaluated against the APHA method under laboratory conditions using a common sewage coliphage strain as a model (American Type Culture Collection- 13706-B2), and under field conditions using water samples collected from four different sources. During the laboratory evaluation, both the LCPA and CAB methods were found to be superior in coliphage detection to the APHA method because: 1) the LCPA and CAB methods were easier to read and interpret than the APHA method, 2) the LCPA and CAB methods were not subject to false positive results, 3) the LCPA method theoretically detected fewer coliphage particles than the APHA method, and 4) the CAB method detected roughly twice the number of coliphage particles than the APHA method. During the field evaluation, the results indicated: 1) the LCP A method was as reliable as either the CAB or APHA methods in coliphage detection, 2) the LCP A and CAB methods were easier to read and interpret than the APHA method, 3) neither the LCPA method nor the CAB method were subject to false positive results, 4) the CAB method detected more coliphages than the APHA method under conditions of high fecal pollution, but both methods performed equally well in coliphage detection under conditions of low fecal contamination, and 5) the LCPA and CAB methods were equally as sensitive in coliphage detection as the APHA method. Finally, the coliphage group proved to be a useful indicator of fecal pollution in nonpotable water supplies that exhibited a high degree of fecal pollution, whereas they were not shown to be useful indicators in potable water supplies that exhibited low levels of fecal contamination. The lack of coliphage detection sensitivity under conditions of low fecal contamination does not appear to be method limited, but rather the result of inefficiencies in processing environmental samples using the concentration methods currently available.
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    Evaluation of shallow-placed low pressure distribution systems in soils marginally suited for on-site waste treatment
    Ijzerman, M. Marian (Virginia Tech, 1990-06-14)
    Two shallow-placed low pressure distribution (LPD) systems were evaluated in soils that were marginally suited for a conventional on-site wastewater disposal system (OSWDS) because of low hydraulic conductivity and shallow depth of soil to bedrock. The soils used for this study were Edom (fine, illitic, mesic, Typic Hapludult) and Penn-Bucks soil (fine-loamy, mixed, mesic, ultic Hapludult). In the Edam soil, the LPD system was installed with four subsystem designs operating: a narrow trench design with a design loading rate of 17.5 Lpd/m², and three designs based on Virginia regulations with design loading rates of 9.0 Lpd/m², 4.5 Lpd/m², and 5.7 Lpd/m². In the Penn-Bucks soil, the LPD system was installed with three subsystem designs operating: a narrow trench design with a design loading rate of 30.6 Lpd/m², and two designs based on Virginia regulations with design loading rates of 14.3 Lpd/m², and 7.3 Lpd/m². The evaluation was conducted under different moisture and temperature conditions (summer of 1989, and the winter of 1990), and focused on the fate and transport below each system of two antibiotic resistant Escherichia coli strains and two host-specific bacteriophage strains. The potential loss of N0₃"-N through the biological process of denitrification was also examined. In the Edom soil, a narrow trench design, and designs based on the Virginia regulation all removed >99.9% of the bacterial and viral tracers during the summer of 1989, and >99% during the winter of 1990 throughout a 152 cm depth. The potential loss of N0₃"-N in the Edom soil by denitrification was estimated to be 38%. In the Penn-Bucks soil, the narrow trench design failed within six months of installation because the effluent loading rate was too high to permit infiltration through the silty clay loam soil, once biological clogging developed with the subsequent decrease in infiltrative capacity. The lower Virginia loading rate was mlore effective at microbial retention with >99.9% removal throughout a 114 cm depth in both the summer of 1989 and the winter of 1990. The normal Virginia loading rate removed> 99% of the bacterial and viral tracers throughout a 102 cm depth in both the summer of 1989 and the winter of 1990. The overall loss of N0₃"-N in the Penn-Bucks soil through denitrification was estimated at 67%.
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    Water sample viral contamination detection system
    (United States Patent and Trademark Office, 1996-06-18)
    Viral contamination in water samples is detected using a medium which includes both a substrate for .beta.-galactosidase and E. coli with elevated levels of intracellular .beta.-galactosidase. The substrate is chosen to undergo a detectable change (e.g., colorimetric, fluorometric, photometric, etc.) upon cleavage by .beta.-galactosidase. A water sample to be tested for viral contamination is added to the medium. If coliphages are present in the water sample, they will infect, multiply within, and subsequently lyse the E. coli host. Lysis of the E. coli will allow the release of the intracellular .beta.-galactosidase into the media, whereupon the enzyme will cleave the substrate for a detectable reaction. In one particular application, a colorimetric reagent that serves as a substrate for .beta.-galactosidase is dissolved or dispersed within an agar medium, and in another particular application, a colorimetric reagent that serves as a substrate for .beta.-galactosidase is dissolved or dispersed within a liquid medium. Color changes which result from lytic cell infection of the E. coli hosts are easily monitored by researchers or laboratory technicians. The presence of coliphages in a water sample is indicative of the presence of harmful human and animal enteric viruses in the water.