Flow cytometry for microbial sensing in environmental sustainability applications: current status and future prospects

Abstract

Practical and accurate microbial assessment of environmental systems is predicated on the detection and quantification of various microbial parameters in complex matrices. Traditional growth-based assays, considered to be both slow and biased, are increasingly being replaced by optical detection methods such as flow cytometry. Flow cytometry (FCM) offers high-speed multi-parametric data acquisition, compatibility with current molecular-based microbial detection technologies, and is a proven technology platform. The unique technical properties of flow cytometry have allowed the discrimination of bacteria based on nucleic acid staining, microbial identification based on genomic and immunologic characteristics, and determination of cell viability. For this technology to achieve the ultimate goal of monitoring the microbial ecology of distributed systems, it will be necessary to develop a fully functional, low cost, and networkable microsystem platform capable of rapid detection of multiple species of microorganisms simultaneously under realistic environmental conditions. One such microsystem, miniaturized and integrated in accordance with recent advances in micro-electro-mechanical systems technology, is named the Micro Integrated Flow Cytometer. This manuscript is a minireview of the current status and future prospects for environmental application of flow cytometry in general, and micro-flow cytometry in particular.

Giardia diagnostic methods in human fecal samples: A comparative study

“…Another study reported that FC had the same specificity as conventional staining methods in detection of Cyclospora in human stool samples, while it was inferior to RT-PCR (30). Gruden et al (31) stated that despite the speed, sensitivity, and reproducibility, documented FC applications in complex environmental matrices are virtually nonexistent as these samples pose the challenge of a broad range of biogeochemical conditions (ionic strength, pH, particulate matter), which may impact label specificity, fluorescent response, and method sensitivity. Uehlinger et al (25) reported that the subjectivity in the counting process by FC introduced by the operator's decision ,on what to include in or exclude from the counting process with electronic gating, makes FC inferior to DIF for Giardia detection in stool.…”

Development of a "genome-proxy" microarray for profiling marine microbial communities, and its application to a time series in Monterey Bay, California

“…In addition, advances in FCM, such as equipment miniaturization, are bringing down costs and enabling novel field deployments (Gruden et al, 2004, Yang et al, 2006. Perhaps pinnacle among these field efforts are the "FlowCytoBot" (Olson and Sosik, 2007;Sosik and Olson, 2007) and "Cytosub" (Thyssen et al, 2008) which use robotics and autonomous sampling devices to enable in situ real-time FCM.…”

Nano-Immunodetection and Quantification of Mycobacteria in Metalworking Fluids

“…In the past decade, flow cytometry (FCM) has been increasingly used for direct optical detection of bacteria in aquatic systems and in environmental samples with complex matrix characteristics (Porter et al, 1997;VivesRego et al, 2000;Gruden et al, 2004). FCM technology is based on optical detection of particles within a sample stream hydrodynamically focused by sheath fluid in a flow cell, where incident light is introduced by a laser source (BD-Biosciences, 2001).…”

“…Particles exhibit different light-scattering characteristics due to their size, internal complexity, granularity, and fluorescence due to specific dyes. Recent reviews on FCM applications in complex environmental matrices can be found elsewhere (Veal et al, 2000;Gruden et al, 2004).…”