Identification and measurement of bacterial size using the ImageStream

In this note, we describe two bacterial studies performed using the ImageStream high speed imaging cytometer. In the first system, pathogenic bacteria are distinguished from microflora and debris normally present in alfalfa seed sprouts. Because the aerobic conditions necessary for sprout growth also foster microbial growth, sprouts harbor a diverse microflora, including potential human pathogens. Salmonella spp., probed using a novel FISH method, are detected within complex sprout preparations by combining fluorescence/SSC intensity-based measurements with morphologic confirmation of gated populations. In the second study we measure length of individual bacteria for large populations of E.Coli and Cyanobacteria to follow bacterial growth in culture. By combining high speed image collection with quantitative imagebased measurements, the ImageStream enables accurate identification and classification of bacteria within heterogeneous samples.

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