Abstract: A method of identifying the taxonomic or functional classification of cells in situ involves labeling the cells with a set of nucleic acid probes and performing combinatorial fluorescence microscopic imaging. The set of probes contains groups of either two or three probes that bind to a taxon-specific or function-specific nucleotide sequence. Each probe of a group of probes is labeled with a distinct fluorescent label, and each group corresponds to a unique combination of labels, which can be detected across the image and serves to identify cells having a single target sequence, or a set of target sequences, that are characteristic of a unique taxonomic or functional classification. The combinatorial labeling and spectral imaging approach greatly expands the number of different classifications that can be identified simultaneously in a single image of a collection of cells.

Abstract: A method of identifying the classification of cells in situ involves labeling the cells with a set of nucleic acid probes and performing combinational fluorescence microscopic imaging. The set of probes contains groups of probes that bind to a taxon-specific or function-specific nucleotide sequence. Each probe of a group of probes is labeled with a distinct fluorescent label, and each group corresponds to a unique combination of labels, which can be detected across the image and serves to identify cells according to a unique taxonomic or functional classification. The combinational labeling and spectral imaging approach expands the number of different classifications that can be identified simultaneously in a single image of a collection of cells. The methods and probe sets of the invention can be used to rapidly identify microbes, study their ecological relationships, screen for novel antibiotics, and identify pathogens.