First, you need to retrieve the FASTA sequences of the already sequenced genes. After that, you should make a sequence alignment on a software like CLUSTALW (https://www.ebi.ac.uk/Tools/msa/clustalw2/) to seek for the conserved regions of the gene. Based on this regions, you will design your FISH probe, which for bacteria can start in 33 bp (Ming Tan <em>et al.</em>, 2019), but a 200 bp probe is a very suitable size. There are several companies that fabricates this custom probes, and sell all the reagents to perform the experiments. Having this, you will perform your FISH experiment to see which cells are actively degrading Toluene.
