Flow cytometry, bacteria

Flow cytometry has been employed to detect the presence E. coli in each of six air samples taken during experiments. Where coloiy-counting techniques are limited to detecting only culturable (i.e., visibly growing) bacteria, flow cytometry is capable of detecting the physical presence of bacteria in a sample regardless of culturabihty. Flow cytometry analysis... 

J. Porter, C. Edwards, J. A. W. Morgan, and R. W. Pickup, Rapid, automated separation of specific bacteria from lake water and sewage by flow cytometry and cell sorting, Appl. Environ. Microbiol. 59 3327 (1993). 

Several additional instrumental techniques have also been developed for bacterial characterization. Capillary electrophoresis of bacteria, which requires little sample preparation,42 is possible because most bacteria act as colloidal particles in suspension and can be separated by their electrical charge. Capillary electrophoresis provides information that may be useful for identification. Flow cytometry also can be used to identify and separate individual cells in a mixture.11,42 Infrared spectroscopy has been used to characterize bacteria caught on transparent filters.113 Fourier-transform infrared (FTIR) spectroscopy, with linear discriminant analysis and artificial neural networks, has been adapted for identifying foodbome bacteria25,113 and pathogenic bacteria in the blood.5... 

Aquatic single cell organisms with a size range of about 0.02-200 pm in diameter occur in nature in concentrations that range from about 102 to 107 per ml. They include viruses, bacteria, cyanobacteria (formerly known as blue-green algae), autotrophic phytoplankton (unicellular plants), and heterotrophic zooplankton (unicellular animals). The analysis of aquatic organisms by flow cytometry presents... 

Fig. 11.12. The use of gel microdroplets and flow cytometry to assay drug sensitivity of bacterial cells. The figure shows side scatter and green fluorescence contour plots of gel microdroplets (GMDs) containing E. coli cells that have been stained with fluorescein isothiocyanate for total protein. The microdroplets have been analyzed in the flow cytometer either at time 0 or 2 h after incubation in control medium (left plots) or medium containing penicillin (right plots). A model system was created by mixing two strains of bacteria (susceptible or resistant to penicillin). The data show that a small subpopulation of resistant cells could be detected within 2 h because of its rapid growth in comparison to susceptible cells. From Weaver et al. (1991).

Suzuki K, Hinuma A, Saito H, Kiyosawa H, Liu H, Saino T et al (2005) Response of phytoplankton and heterotrophic bacteria in the northwest subarctic Pacific to in situ iron fertilization as estimated by HPLC pigment analysis and flow cytometry. Prog Oceanogr. DOI 10.1016/j.po-cean.2005.02.007... 

Gasol,. M., Zweifel, U. L., Peters, F., Fuhrman,. A., andHagstrom, A. (1999). Significance of size and nucleic acid content heterogeneity as measured by flow-cytometry in natural planktonic bacteria. Appl. Environ. Microbiol. 65, 4475—4483. 

Marie, D., Bmssaard, C. P. D., Thyrhaug, R., Bratbak, G., and VarJot, D. (1999). Enumeration of marine viruses in culture and natural samples by flow cytometry. Appl. Environ. Microbiol. 65, 45—52. McDaniel, L., and Capone, D. G. (1985). A comparison of procedures for the separation of aquatic bacteria from sediments for subsequen direct enumeration. J. Microbiol. Methods 3, 291—302. McDaniel, L., Houchin, L. A., Williamson, S. J., and Pard, J. H. (2002). Lysogeny in marine Synechococcus. Nature 415, 496. 

Flow cytometry can also be used to separate phytoplankton from bacteria and detritus (e.g., Lipshultz, 1995 Casey et al., 2007). Another technique being used to remove detritus from particulate samples is centrifugation with coUoidal silica (Hamilton et al., 2005). With this technique the sample is mixed with the coUoidal silica and then centrifuged. Detritus and living ceUs are separated based on density differences detritus tends to be heavier. 

Tombolini, R., Unge, A., Davey, M.E. and De Bruijn, F.J. (1997) Flow cytometry and microscopic analysis of GFP-tagged Pseudomonas fluorescens bacteria. FEMS Microbiology Ecology, 22, 17-28. 

Lemarchand K, Parthuisot N, Catala P, Lebaron P (2001) Comparative assessment of epifluores-cence microscopy, flow cytometry and solid phase cytometry in the enumeration of specific bacteria in water. Aquat Microb Ecol 25 301-309 Lepeuple AS, Delabre K, GUouppe S, IntertagUa L, de Roubin MR (2003) Laser scanning detection of FISH-labelled Escherichia coli from water samples. Water Sd Technol 47 123-129 Lisle JT, Hamilton MA, Willse AR, McFeters GA (2004) Comparison of fluorescence microscopy and sohd-phase cytometry methods for counting bacteria in water. Appl Environ Microbiol 70 5343-5348... 

Fig. 6.10 Distributions of bacterial abundance at the sea surface during various seasons. Two different methods - epifluorescence microscopy (upper panels) and flow cytometry (lower panels) - were used to enumerate bacteria. Redrawn from Ducklow etal. (2001) with permission from Elsevier Science.

Lange J.L., Thome P.S. and Lynch N.L. (1997) Application of flow cytometry and fluorescent in situ hybridization for assessment of exposures to airborne bacteria. Appl. Environ. Microbiol., 63, 1557-1563. 

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