Spectral Imaging Visually Discriminates Different Microbes

The technique, known as combinatorial labeling and spectral imaging fluorescent in situ hybridization (CLASI-FISH), is faster than traditional ways of identifying the microbes in a sample.

Scientists at the Marine Biological Laboratory (MBL; Woods Hole MA, USA) used the CLASI-FISH method to reveal the spatial structure of the community of microbes in an oral biofilm. They demonstrated a fluorescence-imaging assay capable of distinguishing 28 differently labeled microbes in a single field of view, significantly improving the number of fluorescent labels previously distinguished in microbial fluorescent in situ hybridization (FISH). Their 15-taxon mixture of laboratory-grown oral microbes consisted of cells of varying complexity in their cell wall composition and represented both Gram-positive and Gram-negative organisms.

Cells of the genera Streptococcus and Prevotella were the most abundant, whereas cells of the genera Veillonella, Prevotella, and Actinomyces showed the most interspecies associations including those with Streptococcus, Rothia, Gemella, Pasteurellaceae, Porphyromonas, and Neisseriaceae. In addition, Actinomyces and Prevotella were found to have significant association frequencies with Fusobacterium.

Gary Borisy, PhD, president and director of the MBL, commenting on the method said, "We get information on the presence of many different microbes at once and get it quickly, cheaply, and perhaps more accurately than other methods. It is very possible that this technology will enable a new kind of clinical diagnostic procedure, so that it will be possible to very quickly and accurately diagnose a specimen for many kinds of microbes at once. As an alternative to culturing, it could be faster, cheaper, and better." The study was published online on February 16, 2011, in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

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