•Fluorescent in-situ hybridization
–Design a probe consisting of an oligonucleotide sequence and a tag
–Degree of specificity is variable!
–Hybridize that oligonucleotide sequence to the rRNA of an organism – this is temperature and salt content sensitive
–Image using epiflourescence, laser excitation confocal microscopy
•Technique DIRECTLY images active organisms in a sample
FISH variations