Step 5: Serial dilution and membrane filtration of fecal samples.
Bacteria must be isolated from each fecal sample to provide a database of known-source ribotypes (genetic fingerprints). To do this, project staff conducted a serial dilution of the stuff (from 1:100 to 1:10000000) and then conducted membrane filtration on the dilutions, just as with water samples. The wide range of dilutions allowed us to obtain single colonies on at least one of the petri dishes.

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