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Stibal M, Gözdereliler E, Cameron KA, Box JE, Stevens IT, Gokul JK, Schostag M, Zarsky JD, Edwards A, Irvine-Fynn TDL, Jacobsen CS. Microbial abundance in surface ice on the Greenland Ice Sheet. Front Microbiol 2015; 6:225. [PMID: 25852678 PMCID: PMC4371753 DOI: 10.3389/fmicb.2015.00225] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 03/06/2015] [Indexed: 12/03/2022] Open
Abstract
Measuring microbial abundance in glacier ice and identifying its controls is essential for a better understanding and quantification of biogeochemical processes in glacial ecosystems. However, cell enumeration of glacier ice samples is challenging due to typically low cell numbers and the presence of interfering mineral particles. We quantified for the first time the abundance of microbial cells in surface ice from geographically distinct sites on the Greenland Ice Sheet (GrIS), using three enumeration methods: epifluorescence microscopy (EFM), flow cytometry (FCM), and quantitative polymerase chain reaction (qPCR). In addition, we reviewed published data on microbial abundance in glacier ice and tested the three methods on artificial ice samples of realistic cell (102–107 cells ml−1) and mineral particle (0.1–100 mg ml−1) concentrations, simulating a range of glacial ice types, from clean subsurface ice to surface ice to sediment-laden basal ice. We then used multivariate statistical analysis to identify factors responsible for the variation in microbial abundance on the ice sheet. EFM gave the most accurate and reproducible results of the tested methodologies, and was therefore selected as the most suitable technique for cell enumeration of ice containing dust. Cell numbers in surface ice samples, determined by EFM, ranged from ~ 2 × 103 to ~ 2 × 106 cells ml−1 while dust concentrations ranged from 0.01 to 2 mg ml−1. The lowest abundances were found in ice sampled from the accumulation area of the ice sheet and in samples affected by fresh snow; these samples may be considered as a reference point of the cell abundance of precipitants that are deposited on the ice sheet surface. Dust content was the most significant variable to explain the variation in the abundance data, which suggests a direct association between deposited dust particles and cells and/or by their provision of limited nutrients to microbial communities on the GrIS.
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Affiliation(s)
- Marek Stibal
- Geological Survey of Denmark and Greenland Copenhagen, Denmark ; Center for Permafrost, University of Copenhagen Copenhagen, Denmark ; Department of Ecology, Charles University in Prague Prague, Czech Republic
| | - Erkin Gözdereliler
- Geological Survey of Denmark and Greenland Copenhagen, Denmark ; Center for Permafrost, University of Copenhagen Copenhagen, Denmark
| | - Karen A Cameron
- Geological Survey of Denmark and Greenland Copenhagen, Denmark ; Center for Permafrost, University of Copenhagen Copenhagen, Denmark
| | - Jason E Box
- Geological Survey of Denmark and Greenland Copenhagen, Denmark
| | - Ian T Stevens
- Centre for Glaciology, Aberystwyth University Aberystwyth, UK
| | | | - Morten Schostag
- Center for Permafrost, University of Copenhagen Copenhagen, Denmark
| | - Jakub D Zarsky
- Department of Ecology, Charles University in Prague Prague, Czech Republic ; Centre for Polar Ecology, University of South Bohemia České Budějovice, Czech Republic
| | - Arwyn Edwards
- Centre for Glaciology, Aberystwyth University Aberystwyth, UK
| | | | - Carsten S Jacobsen
- Geological Survey of Denmark and Greenland Copenhagen, Denmark ; Center for Permafrost, University of Copenhagen Copenhagen, Denmark ; Department of Plant and Environmental Sciences, University of Copenhagen Copenhagen, Denmark
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Ruiz-González C, Simó R, Sommaruga R, Gasol JM. Away from darkness: a review on the effects of solar radiation on heterotrophic bacterioplankton activity. Front Microbiol 2013; 4:131. [PMID: 23734148 PMCID: PMC3661993 DOI: 10.3389/fmicb.2013.00131] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 05/06/2013] [Indexed: 12/22/2022] Open
Abstract
Heterotrophic bacterioplankton are main consumers of dissolved organic matter (OM) in aquatic ecosystems, including the sunlit upper layers of the ocean and freshwater bodies. Their well-known sensitivity to ultraviolet radiation (UVR), together with some recently discovered mechanisms bacteria have evolved to benefit from photosynthetically available radiation (PAR), suggest that natural sunlight plays a relevant, yet difficult to predict role in modulating bacterial biogeochemical functions in aquatic ecosystems. Three decades of experimental work assessing the effects of sunlight on natural bacterial heterotrophic activity reveal responses ranging from high stimulation to total inhibition. In this review, we compile the existing studies on the topic and discuss the potential causes underlying these contrasting results, with special emphasis on the largely overlooked influences of the community composition and the previous light exposure conditions, as well as the different temporal and spatial scales at which exposure to solar radiation fluctuates. These intricate sunlight-bacteria interactions have implications for our understanding of carbon fluxes in aquatic systems, yet further research is necessary before we can accurately evaluate or predict the consequences of increasing surface UVR levels associated with global change.
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Affiliation(s)
- Clara Ruiz-González
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSICBarcelona, Spain
- Département des Sciences Biologiques, Université du Québéc à MontréalMontréal, QC, Canada
| | - Rafel Simó
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSICBarcelona, Spain
| | - Ruben Sommaruga
- Laboratory of Aquatic Photobiology and Plankton Ecology, Institute of Ecology, University of InnsbruckInnsbruck, Austria
| | - Josep M. Gasol
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSICBarcelona, Spain
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Zhu T, Xu X. Efficacy of a dual fluorescence method in detecting the viability of overwintering cyanobacteria. Lett Appl Microbiol 2013; 57:174-80. [PMID: 23627896 DOI: 10.1111/lam.12095] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 04/16/2013] [Accepted: 04/16/2013] [Indexed: 11/29/2022]
Abstract
Chill in the light is the major environmental stress that cyanobacteria encounter in winter. Cyanobacterial cells may acquire chill-light tolerance upon exposure to low temperature in autumn and early winter. We sought to establish the efficacy of the dual fluorescence method in detecting the viability of overwintering cyanobacteria and to provide further evidence for the chill-light tolerance of preconditioned cyanobacteria. Synechocystis sp. PCC 6803 and Microcystis aeruginosa PCC 7806 were exposed to chill (5°C)-light stress with or without pretreatment at 15°C and stained with SYTO 9 and propidium iodide. Live and dead cells were observed under a fluorescence microscope, and the percentage of viable cells was quantified on a microplate reader. The dual fluorescence method showed consistent results with tests of the ability to reinitiate growth. Cell viability was quantitatively correlated with ratio of SYTO 9/propidium iodide fluorescence. Previously, Microcystis colonies in Lake Taihu had been found to accumulate RNA-binding protein 1 in autumn and winter. Use of this method directly showed the viability of such Microcystis colonies throughout the winter.
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Affiliation(s)
- T Zhu
- CAS Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China
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Johnson S, Nguyen V, Coder D. Assessment of cell viability. CURRENT PROTOCOLS IN CYTOMETRY 2013; Chapter 9:9.2.1-9.2.26. [PMID: 23546778 DOI: 10.1002/0471142956.cy0902s64] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cell viability may be judged by morphological changes or by changes in membrane permeability and/or physiological state inferred from the exclusion of certain dyes or the uptake and retention of others. This unit presents methods based on dye exclusion, esterase activity, and mitochondrial membrane potential, as well as protocols for determining the pre-fixation viability of fixed cells either before or after fixation with amine-reactive dyes suitable for a range of excitation wavelengths. Membrane-impermeable dead cell and live cell dyes as well as dye-exclusion procedures for microscopy are also included.
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Affiliation(s)
- Simon Johnson
- University of Washington School of Medicine, Seattle, Washington
| | - Vy Nguyen
- University of Washington School of Medicine, Seattle, Washington
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Salma M, Rousseaux S, Sequeira-Le Grand A, Alexandre H. Cytofluorometric detection of wine lactic acid bacteria: application of malolactic fermentation to the monitoring. ACTA ACUST UNITED AC 2013; 40:63-73. [DOI: 10.1007/s10295-012-1200-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 09/15/2012] [Indexed: 11/29/2022]
Abstract
Abstract
In this study we report for the first time a rapid, efficient and cost-effective method for the enumeration of lactic acid bacteria (LAB) in wine. Indeed, up to now, detection of LAB in wine, especially red wine, was not possible. Wines contain debris that cannot be separated from bacteria using flow cytometry (FCM). Furthermore, the dyes tested in previous reports did not allow an efficient staining of bacteria. Using FCM and a combination of BOX/PI dyes, we were able to count bacteria in wines. The study was performed in wine inoculated with Oenococcus oeni (106 CFU ml−1) stained with either FDA or BOX/PI and analyzed by FCM during the malolactic fermentation (MLF). The analysis show a strong correlation between the numbers of BOX/PI-stained cells determined by FCM and the cell numbers determined by plate counts (red wine: R2 ≥ 0.97, white wine R2 ≥ 0.965). On the other hand, we found that the enumeration of O. oeni labeled with FDA was only possible in white wine (R2 ≥ 0.97). Viable yeast and LAB populations can be rapidly discriminated and quantified in simultaneous malolactic-alcoholic wine fermentations using BOX/PI and scatter parameters in a one single measurement. This rapid procedure is therefore a suitable method for monitoring O. oeni populations during winemaking, offers a detection limit of <104 CFU ml−1 and can be considered a useful method for investigating the dynamics of microbial growth in wine and applied for microbiological quality control in wineries.
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Affiliation(s)
- Mohammad Salma
- grid.5613.1 0000000122989313 UMR 02102 PAM Université de Bourgogne-AgroSup Dijon Laboratoire VALMIS Institut Universitaire de la Vigne et du Vin Jules Guyot Université de Bourgogne 21078 Dijon Cedex France
| | - Sandrine Rousseaux
- grid.5613.1 0000000122989313 UMR 02102 PAM Université de Bourgogne-AgroSup Dijon Laboratoire VALMIS Institut Universitaire de la Vigne et du Vin Jules Guyot Université de Bourgogne 21078 Dijon Cedex France
| | - Anabelle Sequeira-Le Grand
- grid.5613.1 0000000122989313 Plateforme de Cytométrie, Structure Fédérative de Recherche Santé STIC, Fac. Médecine Université de Bourgogne 7, Bd Jeanne D’Arc 21000 Dijon France
| | - Hervé Alexandre
- grid.5613.1 0000000122989313 UMR 02102 PAM Université de Bourgogne-AgroSup Dijon Laboratoire VALMIS Institut Universitaire de la Vigne et du Vin Jules Guyot Université de Bourgogne 21078 Dijon Cedex France
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Kim JS, Nam MH, An SSA, Lim CS, Hur DS, Chung C, Chang JK. Comparison of the automated fluorescence microscopic viability test with the conventional and flow cytometry methods. J Clin Lab Anal 2011; 25:90-4. [PMID: 21437999 DOI: 10.1002/jcla.20438] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The cell viability test is an essential tool in any laboratory, performing cell-based studies and clinical laboratory tests. The trypan blue exclusion method is the most popular assay for its simple concept among various diagnostic tools. However, several disadvantages include time-consuming and labor-intensive steps with low precision. In this study, we evaluated a new technique for the automatic cell viability measurement with microscopic cell counter and microchip. Upon blood draw from 11 healthy volunteers, Mononuclear cells were separated immediately from the heparinized whole blood, and the viable cells were diluted from 100 to 1%. The cell viability tests were performed simultaneously with following three methods: the conventional manual trypan blue exclusion method; the flow cytometry measurement with propidium iodide stain; and the newly developed microscopic cell counter with microchip. Linearities, precisions, and correlations from three methods were analyzed and compared. The correlations data from the microscopic cell counter were in good agreement with both the conventional trypan blue method (r=0.99, P<0.05) and the flow cytometry (r=0.99, P<0.05), respectively. The precision (2.0-6.2%) and linearity from the microscopic cell counter method with microchip were superior in comparison with the conventional method. The microscopic cell counter with microchip performed well with high precision, linearity, and efficient running time than both the manual trypan blue and the flow cytometry methods.
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Affiliation(s)
- Jang Su Kim
- Department of Laboratory Medicine, Seoul, Republic of Korea
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Kaprelyants AS, Mukamolova GV, Davey HM, Kell DB. Quantitative Analysis of the Physiological Heterogeneity within Starved Cultures of Micrococcus luteus by Flow Cytometry and Cell Sorting. Appl Environ Microbiol 2010; 62:1311-6. [PMID: 16535295 PMCID: PMC1388833 DOI: 10.1128/aem.62.4.1311-1316.1996] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A high proportion of Micrococcus luteus cells in cultures which had been starved for 3 to 6 months lost the ability to grow and form colonies on agar plates but could be resuscitated from their dormancy by incubation in an appropriate liquid medium (A. S. Kaprelyants and D. B. Kell, Appl. Environ. Microbiol. 59:3187-3196, 1993). We used flow cytometry and cell sorting to study populations of bacteria that had been starved for 5 months. These cells could be stained by the fluorescent lipophilic cation rhodamine 123, but such staining was almost independent of metabolically generated energy in that it was not affected by uncouplers. Two populations could be distinguished, one with a lower degree of rhodamine fluorescence (a degree of fluorescence referred to as region A and containing approximately 80% of the cells) and one with a more elevated degree of fluorescence (region B, approximately 20% of the cells). Subsequent incubation of starved cells in fresh medium in the presence of the antibiotic chloramphenicol (to which M. luteus is sensitive) resulted in the transient appearance of cells actively accumulating rhodamine 123 (and fluorescing in region B) and of larger cells exhibiting a yet-greater degree of fluorescence (region C). These more fluorescent cells accounted for as much as 50% of the total population, under conditions in which the viable and total counts were constant. Thus, metabolic resuscitation of at least one-half of the cells takes place under conditions in which cryptic growth cannot play any role. Sorting experiments revealed that the great majority of the viable cells in the starved population are concentrated in regions B and C and that the extent of rhodamine staining under conditions of starvation therefore reflects the physiological state of the cells. Physical separation of these cells from cells in region A resulted in an increase (of approximately 25-fold) in the viability of cells in regions B and C and of the population as a whole. Resuscitation of dormant cells in a most-probable-number assay in the presence of supernatant taken from growing M. luteus revealed the resuscitation of cells from regions B and C but not from region A. It is suggested that initially dormant (resuscitable) cells are concentrated in regions B and C.
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Porter J. Flow cytometry and environmental microbiology. CURRENT PROTOCOLS IN CYTOMETRY 2008; Chapter 11:Unit 11.2. [PMID: 18770789 DOI: 10.1002/0471142956.cy1102s27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This survey unit discusses many of the issues involved for flow cytometry in the field of microbiology, particularly the preparative procedures, which are far more stringent than many other procedures using larger cells. For instance, it is often necessary to filter laboratory agents multiple times to obtain the true particle-free solutions needed for flow cytometry of microbes. It is difficult enough to recognize bacteria in cell extracts from soil, sediment, or sludge given the background of same-size particles. This unit provides an excellent overview of a potentially large application area in flow cytometry and is written by one of the most respected scientists in the field.
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Griffin DW. Atmospheric movement of microorganisms in clouds of desert dust and implications for human health. Clin Microbiol Rev 2007; 20:459-77, table of contents. [PMID: 17630335 PMCID: PMC1932751 DOI: 10.1128/cmr.00039-06] [Citation(s) in RCA: 331] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Billions of tons of desert dust move through the atmosphere each year. The primary source regions, which include the Sahara and Sahel regions of North Africa and the Gobi and Takla Makan regions of Asia, are capable of dispersing significant quantities of desert dust across the traditionally viewed oceanic barriers. While a considerable amount of research by scientists has addressed atmospheric pathways and aerosol chemistry, very few studies to determine the numbers and types of microorganisms transported within these desert dust clouds and the roles that they may play in human health have been conducted. This review is a summary of the current state of knowledge of desert dust microbiology and the health impact that desert dust and its microbial constituents may have in downwind environments both close to and far from their sources.
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Affiliation(s)
- Dale W Griffin
- U.S. Geological Survey, St. Petersburg, Florida 33701, USA.
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10
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Ferrari BC, Stoner K, Bergquist PL. Applying fluorescence based technology to the recovery and isolation of Cryptosporidium and Giardia from industrial wastewater streams. WATER RESEARCH 2006; 40:541-8. [PMID: 16426657 DOI: 10.1016/j.watres.2005.11.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Revised: 11/21/2005] [Accepted: 11/25/2005] [Indexed: 05/06/2023]
Abstract
As increasing water shortages continue, water re-use is posing new challenges with treated wastewater becoming a significant source of non-potable water. Rapid detection strategies that target waterborne pathogens of concern to industry are gaining importance in the assessment of water quality. This study reports on the ability to recover spiked Cryptosporidium and Giardia from a variety of industrial wastewater streams of varied water quality. Incorporation of an internal quality control used commonly in finished water-enabled quantitative assessments of pathogen loads and we describe successful analysis of pre- and part-treated wastewater samples from four industrial sites. The method used combined calcium carbonate flocculation followed by flow cytometry and epifluorescence microscopy. Our focus will now aim at characterising the ambient parasites isolated from industrial wastewater with the objective of developing a suite of highly specific platform detection technologies targeted to industrial needs.
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Affiliation(s)
- B C Ferrari
- Department of Chemistry and Biomolecular Sciences, Environmental Biotechnology CRC and Biotechnology Research Institute, Macquarie University Sydney, NSW 2109, Australia.
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Morgan CA, Bigeni P, Herman N, Gauci M, White PA, Vesey G. Production of precise microbiology standards using flow cytometry and freeze drying. ACTA ACUST UNITED AC 2004; 62:162-8. [PMID: 15517560 DOI: 10.1002/cyto.a.20075] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Quality control standards provide a quantity of microorganisms for routine use in microbiology to demonstrate the efficacy of testing methods and culture media. Standards are normally prepared by diluting a culture of microorganisms to obtain a suspension that contains an estimated number of colony-forming units per milliliter. The variability and inaccuracy of these standards increase the potential for false results. Flow cytometry has been used extensively to prepare precise standards of Cryptosporidium and Giardia that contain exact numbers of organisms in a volume of liquid (1). However, the same levels of accuracy have yet to be obtained for bacterial quality control standards. METHODS A modification of a Becton Dickinson FACScalibur flow cytometer enabled 30 bacterial cells to be sorted into a single droplet, mixed with a cryoprotective solution within the droplet, and frozen in liquid nitrogen. The frozen droplets were then freeze dried for stable preservation of the viable bacterial cells. RESULTS A freeze-dried sphere 3 mm in diameter was produced, which contained 30 microorganisms. The within-batch variation for these freeze-dried spheres was no greater than two standard deviations, and the between-batch variation was less than one standard deviation. CONCLUSIONS Bacterial reference controls can now be produced with consistent accuracy and unparalleled precision, thus enabling harmonization across the microbiological testing industry.
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Affiliation(s)
- C A Morgan
- BTF Pty. Ltd., North Ryde, New South Wales, Australia.
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13
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Chesnot T, Marly X, Chevalier S, Estévenon O, Buès M, Schwartzbrod J. Optimised immunofluorescence procedure for enumeration of Cryptosporidium parvum oocyst suspensions. WATER RESEARCH 2002; 36:3283-3288. [PMID: 12188126 DOI: 10.1016/s0043-1354(02)00032-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The aim of this study was to evaluate an optimised immunofluorescence assay in terms of the variability of sets of counts for Cryptosporidium parvum oocyst suspensions and data recovery and the reliability of the procedure. A coefficient of variation (CV) of 10% was determined to be the maximum value acceptable for count variability. It was found that the optimised IFA tested provided a high precision for the sets of enumerations for suspensions containing 800-20,000 oocysts/mL. The procedure was found to be robust and providing high recovery level (96.3%). In terms of counting precision, the technique described here approaches the performance of flow cytometry and surpasses other manual techniques with a CV of 10% for a concentration close to 800 oocysts/mL. The procedure described is particularly suitable for the production of seed doses and for other applications requiring the titration of oocyst suspensions with a high degree of precision and accuracy.
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Affiliation(s)
- T Chesnot
- Laboratoire de parasitologie, Faculté de pharmacie, LCPME-UMR 7564 CNRS-UHP, Nancy, France.
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Affiliation(s)
- David M. Coder
- University of Washington School of Medicine Seattle Washington
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15
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Thomas JC, St-Pierre Y, Beaudet R, Villemur R. Monitoring by laser-flow-cytometry of the polycyclic aromatic hydrocarbon-degrading Sphingomonas sp. strain 107 during biotreatment of a contaminated soil. Can J Microbiol 2000; 46:433-40. [PMID: 10872079 DOI: 10.1139/w00-008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A flow cytometric method (FCM) was used to detect and accurately enumerate a polycyclic aromatic hydrocarbon-degrading bacterial strain, Sphingomonas sp. 107, inoculated into a soil sample artificially contaminated with pyrene. To compare the FCM method with colony forming unit (CFU) assays, a rifampicin-resistant Sphingomonas sp. 107 was obtained which could be distinguished from the indigenous microflora, since there was no organism resistant to rifampicin in the soil that could transform indole to indigo (naphthalene dioxygenase activity). By combining light-scattering profiles (i.e., morphological properties), ethidium bromide influx (i.e., cell wall permeability), and fluorescence in situ hybridization against the 16S rRNA (i.e., detection specificity), we could enumerate the bacterial population of interest from the indigenous microflora and soil debris during the biotreatment. The FCM technique revealed that the number of inoculated Sphingomonas cells decreased gradually for 15 days of incubation before reaching a steady level of 7 to 12 x 10(5) cells.g-1 of soil. Similar values were obtained with the CFU assay. During this period, pyrene concentration decreased from 632 to 26 mg.kg-1 of dry soil. The FCM detection was improved by adding blocking reagent to the hybridization buffer to minimize the non-specific attachment of the fluorescent probe to soil particles. Combined with the improvements in probe technology, FCM detection was shown to be a good alternative to the conventional culture methods for the analysis of bacterial populations in environmental samples. This technique could be potentially useful for the detection of microorganisms that grow poorly in culture.
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Affiliation(s)
- J C Thomas
- INRS, Institut Armand-Frappier, Microbiologie et Biotechnologie, Laval, Canada
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Gunasekera TS, Attfield PV, Veal DA. A flow cytometry method for rapid detection and enumeration of total bacteria in milk. Appl Environ Microbiol 2000; 66:1228-32. [PMID: 10698799 PMCID: PMC91970 DOI: 10.1128/aem.66.3.1228-1232.2000] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Application of flow cytometry (FCM) to microbial analysis of milk is hampered by the presence of milk proteins and lipid particles. Here we report on the development of a rapid (</=1-h) FCM assay based on enzymatic clearing of milk to determine total bacteria in milk. When bacteria were added to ultra-heat-treated milk, a good correlation (r >/= 0.98) between the FCM assay and the more conventional methods of plating and direct microscopic counting was achieved. Raw milk data showed a significant correlation (P < 0.01) and a good agreement (r = 0.91) between FCM and standard plate count methods. The detection limit of the FCM assay was </=10(4) bacteria ml of milk(-1). This limit is below the level of detection required to satisfy legislation in many countries and states.
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Affiliation(s)
- T S Gunasekera
- Centre for Fluorimetric Applications in Biotechnology, Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
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17
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Ferrari BC, Vesey G, Davis KA, Gauci M, Veal D. A novel two-color flow cytometric assay for the detection ofCryptosporidium in environmental water samples. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/1097-0320(20001101)41:3<216::aid-cyto9>3.0.co;2-r] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Barardi CR, Emslie KR, Vesey G, Williams KL. Development of a rapid and sensitive quantitative assay for rotavirus based on flow cytometry. J Virol Methods 1998; 74:31-8. [PMID: 9763126 DOI: 10.1016/s0166-0934(98)00061-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A very sensitive and accurate flow cytometry (FC) based method have developed to quantitate rotavirus infection in MA104 cells. Confluent cell monolayers were infected with serial dilutions of rotavirus SA11. After infection, the cells were recovered with the aid of trypsin and then reacted with monoclonal antibody M60 (specific for the rotavirus outer capsid protein, VP7), followed by a second antibody (anti-mouse IgG-FITC). A FACScan FC was used to estimate the number of infected cells, as well as the level of infection. Viral infection was optimised by varying the concentration of trypsin used in the maintenance medium. The FC method enables many cells to be screened quickly for infectivity, and can detect low levels of virus. This method can be adapted to monitor the presence of other viruses in clinical and environmental samples without the need for prolonged periods of adaptation to growth in tissue culture.
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Affiliation(s)
- C R Barardi
- Departamento de Microbiologia e Parasitologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil
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Comas J, Vives-Rego J. Enumeration, viability and heterogeneity in Staphylococcus aureus cultures by flow cytometry. J Microbiol Methods 1998. [DOI: 10.1016/s0167-7012(98)00003-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Dixon BR, Parenteau M, Martineau C, Fournier J. A comparison of conventional microscopy, immunofluorescence microscopy and flow cytometry in the detection of Giardia lamblia cysts in beaver fecal samples. J Immunol Methods 1997; 202:27-33. [PMID: 9075768 DOI: 10.1016/s0022-1759(96)00239-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A variety of domestic and wild animals are considered to be potential sources of giardiasis in humans. As a result, numerous studies have been reported on the prevalence of Giardia lamblia infection in animals. The majority of these surveys have involved various floatation techniques followed by conventional microscopy in order to detect cysts in fecal samples. Immunofluorescence microscopy has become popular in recent years for the detection of G. lamblia cysts in both clinical and environmental samples. This technique can be automated by combining it with flow cytometry. The present study represents a direct comparison of conventional microscopy, immunofluorescence microscopy, and flow cytometry in terms of their relative efficiency in the detection of G. lamblia cysts in beaver fecal samples. As a result of viewer fatigue, or low cyst concentrations, false negatives were common with conventional microscopy, leading to low prevalence estimates. By specifically targeting the cysts, immunofluorescence microscopy provided more reliable results in a shorter time than conventional methods. When flow cytometry was used in combination with immunofluorescence, a larger number of samples could be examined in a relatively short period of time. The results obtained indicated that this technique allowed for more consistent recognition than either conventional or immunofluorescence microscopy of positive samples containing smaller numbers of cysts.
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Affiliation(s)
- B R Dixon
- Bureau of Microbial Hazards, Health Protection Branch, Health Canada, Ottawa, Ont
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Jakubowski W, Boutros S, Faber W, Fayer R, Ghiorse W, LeChevallier M, Rose J, Schaub S, Singh A, Stewart M. Environmental methods for Cryptosporidium. ACTA ACUST UNITED AC 1996. [DOI: 10.1002/j.1551-8833.1996.tb06617.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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