Bacteria: Coliform & E. Coli in Water Test Kit (487197) 12 Tests

Coliform bacteria produce the enzyme β-D-galactosidase which splits the enzyme substrate 5- bromo-4-chloro-3-indolyl-β-D-galactoside (X-GAL). A colored end product is produced; if coliforms are present the liquid sample turns a blue-green color.

E. coli produces the enzyme β3 -D-glucuronidase, which breaks down the enzyme substrate 4- methylumbelliferyl-β-D-g1ucuronide (MUG) to generate an end product. The sample is illuminated with a UV light at about 365nm; if E. coli is present the sample will glow a bright blue, fluorescent, color.

Procedure:

• Wash your hands thoroughly with soap and water
• Carefully remove the bottle cap; do not touch the inside of the cap or bottle opening. Fill with l00mls of the water sample to be tested (about ½" below the neck of the bottle). Do not overfill. Securely recap the bottle.
• Shake the bottle vigorously until all the media is dissolved. The solution should be clear yellow in color (a bit less clear with turbid samples)
• Incubate the sample for:
  • 24 hours at 95° F (35° C) or

  • 48 hours at 77° F (25° C)

Coliform Confirmation:

• After the 24 hour or 48 hour incubation time (based on temperature) observe the color of the sample:
  • Clear yellow negative for coliforms
  • Blue-green = positive for coliforms

E. coil Confirmation:

• Shine a UV light (approximately 365nm) from the bottom of the sample. (Avoid looking directly at the light).
  • No fluorescence negative for E. coli
  • Bright blue fluorescence = positive for E. coli .

If further confirmation of E. coli is desired add 1 ml of Kovacs Indole reagent (sold separately) to the sample, recap the bottle, and wait 30 seconds. A red ring will form if E. coli is present.