JoVE Encyclopedia of Experiments
Microbiology
0 views • 3:48 min • February 26th, 2026
Begin with an adult zebrafish infected with an antibiotic-resistant strain of Vibrio cholerae. This pathogenic bacterium expresses β-galactosidase enzyme and colonizes the intestinal tract.
Collect the fish and transfer it into a solution containing an overdose of anesthetic to euthanize it.
Place the fish ventral side up and secure it with pins.
Disinfect the abdomen, make a longitudinal skin incision and two lateral incisions toward the head, then pin the skin to expose the intestinal tract.
Transfer the tract into a homogenization tube containing a cold buffer with glass beads.
Incubate with agitation, allowing the glass beads to disrupt the tissue and release the bacteria.
Serially dilute the homogenate, plate it onto the medium, and incubate. The medium contains a chromogenic β-galactosidase substrate and an antibiotic to eliminate contaminants.
The bacteria express β-galactosidase enzyme, which hydrolyzes the chromogenic substrate leading to formation of blue-pigmented colonies.
Count the colonies to estimate the intestinal bacterial load.
When the experiment has reached its desired endpoint, take a 15 milliliter sample of the infection water for diagnostic purposes. Then collect the
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