I need info!
Lauryl Maiya J Nutter
lmjnutte at acs5.acs.ucalgary.ca
Thu Oct 5 16:07:02 EST 1995
David Griebeling (dgriebeling at frontier.canrem.com) wrote:
: Hello. I am a student, currently in my last year of high school. I am
: seeking information on Coliform Bacteria, specifically on a method of testing
: for the presence of these bacteria in water.
: If you have any information which may be of use to me, I will be glad
: to hear from you.
: K. Griebeling
: Ontario, Canada
There are several very easy ways to test for the presence of and
differentiate between different species of coliform bacteria in
water. One method is to streak a sample of the water onto EMB
agar (eosine-methylene blue agar). Incubation of the plate
overnight will reveal if bacteria have grown. Different species
have particular colony morphologies on the plate. For example,
E. coli, a lactose-fermenting coliform, produces large colonies
with a green-metallic sheen as a result of the large amount of
acid produced by the fermentation of lactose causing a reaction
between the two dyes in the medium. Salmonella, a non-lactose
fermenter, produces pink colonies. Klebsiella, a non-lactose
fermenter, produces very mucoid pink colonies.
Another form of testing is to use MacConkey broth. This method
tests for the presence of lactose fermenting bacteria (usually
indicative of fecal contamination--ie. coliforms) using a lactose
liquid medium with an indicator dye (I don't remember the name
off the top of my head) in it. An aliquot of the water sample is
added to the medium and incubated at 37C. The dye changes from
purple to yellow when lactose is fermented indicating the
presence of lactose fermeters.
You may want to enquire at the Microbiology Department at your
nearest university or your local water treatment plant for more
I hope the above information at least gives you a starting point
in your search.
University of Calgary
lmjnutte at acs.ucalgary.ca
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