IDENTIFYING MOBILE PLASMIDS IN-SITU IN VARIOUS ECOSYSTEMS

Microbes have various ways of communication, one of which involves transferring plasmids between and among bacterial species- a process termed horizontal gene transfer. This extraordinary phenomenon enables rapid bacterial evolution and gain of function, such as antibiotic resistance. Thus, an increase in horizontal gene transfer rates can be critical in determining the functionality of a given bacterial population.

To investigate the influence of plasmid mobility in various environments, it is essential to identify these plasmids within their host cells (in-situ). A new modification of the well-known Fluorescent in-situ Hybridization method allows us to do so, by hybridizing short probes to plasmids of interest. This Catalyzed Reporter Deposition Single Molecule Fluorescence in-situ Hybridization method, combines enzymatic signal amplification, which increases sensitivity, using small oligonucleotide probes, which are known to increase specificity, to enable the labeling of small and low-copy number plasmids, by using as little as 15 small probes.

Comparing images of labeled mobile plasmids and examining the differences in their distribution throughout microbial communities of different environments, may elucidate their role in these ecosystems.