Bacteria
Bacteria
RiverWatch uses the patented Coliscan Easygel method to test for the presence of coliform bacteria. The growth-medium in the bottles contains inhibitors for non-coliform bacteria and pigment colors that identify coliform bacteria.
Collection
- At the river, use a sterile pipette to add 1 mL of sample water to an Easygel bottle. Label the bottle and keep cool. Dispose of the pipette and wrapper.
Incubation
- Back at school, pour all of the Easygel bottle contents into the sterile and coated Petri dish.
- Seal the Petri dish shut with clear tape. Label the dish.
- If necessary, gently tip the Petri dish to spread the solution evenly.
- Incubate at the warmest room temperature available.
Counting Colonies
- After two days of incubation, count the Coliform bacterial colonies:
|
pink colonies ... |
general coliform bacteria that do not necessarily indicate fecal contamination |
|
purple colonies ... |
fecal coliforms (E.coli) indicating fecal contamination |
|
white, etc. colonies ... |
non-coliform bacteria |
- Check the colonies against white and black backgrounds to highlight colors.
- Counting the total number of pink and purple colonies indicates the number of Coliform bacteria per 1 ml of river water.
- Enter your results on-line at www.riverwatch.ab.ca . Click on "River Data & Maps" then "Enter Collected Data from your Trip".
Disposal
- Open the Petri dish and add a capful of bleach to kill the bacteria. Reseal, tape, swirl and allow to sit for five minutes.
- Dispose in a plastic garbage bag.