Current and future applications of flow cytometry in aquatic microbiology

Abstract

Flow cytometry has become a valuable tool in aquatic and environmental microbiology that combines direct and rapid assays to determine numbers, cell size distribution and additional biochemical and physiological characteristics of individual cells, revealing the heterogeneity present in a population or community. Flow cytometry exhibits three unique technical properties of high potential to study the microbiology of aquatic systems: (i) its tremendous velocity to obtain and process data; (ii) the sorting capacity of some cytometers, which allows the transfer of specific populations or even single cells to a determined location, thus allowing further physical, chemical, biological or molecular analysis; and (iii) high-speed multiparametric data acquisition and multivariate data analysis. Flow cytometry is now commonly used in aquatic microbiology, although the application of cell sorting to microbial ecology and quantification of heterotrophic nanoflagellates and viruses is still under development. The recent development of laser scanning cytometry also provides a new way to further analyse sorted cells or cells recovered on filter membranes or slides. The main infrastructure limitations of flow cytometry are: cost, need for skilled and well-trained operators, and adequate refrigeration systems for high-powered lasers and cell sorters. The selection and obtaining of the optimal fluorochromes, control microorganisms and validations for a specific application may sometimes be difficult to accomplish.

Probiotics - What They Are, Their Benefits and Challenges

“…The intensity of rRNA in dead cells may still be strong enough for visually counting (detection) though it is expected to decrease upon cell death. Thus, the RNA content of the cell detected by fluorescent probes cannot be regarded as reliable indicator of cellular viability (Vives-Rego et al, 2000). Also, real time PCR detects both viable and non-viable bacteria, thus does not provide information on the condition of the cells and results in an overestimation of metabolically active cells (Kramer et al, 2009;Masco et al, 2007).…”

Review: Microbial biocenoses in pristine aquifers and an assessment of investigative methods

“…Escherichia coli (Cassidy et al 2000;Hurst et al 2002;Overmann 2003). Microbial cells can also be directly counted under a microscope or by means of a flow cytometer (Vives-Rego et al 2000). In samples from pristine aquifers, the number of bacteria determined by cultivation techniques is often much lower than the number given by direct counting, because no culture medium is able to match the requirements for all bacterial species present in a sample.…”

Fluorescence resonance energy transfer (FRET)‐based specific labeling of Cryptosporidium oocysts for detection in environmental samples

“…Such autofluorescence is likely to be caused by humic acids and proteins (27) and algal pigments (28). Yet FRET enabled direct qualification of oocysts using the standard 488-nm argon laser in the presence of a vast array of naturally autofluorescent particles (Table 5).…”