rRNA probe‐based cell fishing of bacteria

We have developed a new, cultivation‐independent, fast and flexible method for the rRNA‐targeted probe‐based enrichment of bacteria. The target cells were labelled by in situ hybridization with biotinylated polyribonucleotide probes. These probes were generated by in vitro transcription of amplified rDNA of a variable region in domain III of the 23S rRNA molecules. The probes were about 300 nucleotides in length and were labelled by incorporation of biotin‐UTP during the transcription. Probes were hybridized with bacterial cells and incubated with paramagnetic streptavidin‐coated particles. The labelled target cells can be separated in a column filled with steel wool inserted into the field of a permanent magnet. Unlabelled, non‐target cells pass through the column, whereas labelled cells are retained. They were eluted from the column after removal of the magnetic field. Up to now, the method has been tested with mixtures of different pure cultures. For the first time, transcript probes have been used for the labelling of the target cells and for their specific separation. The enric