1. Principle and application

According to national drinking water sanitary standard, if total coliform is tested from water sample, further test should be done to find it is Escherichia or thermotolerant coliform. If there is not any total coliform tested from water sample, then it is no need to do the further test. 

Filmplate^TM E. coli & thermotolerant colifrom bacteria count plate use enzyme substrate technology, containing X-GLUC/blue which is chromogenic substrate of thermotolerant coliform glucuronidase, as well as X-Gal/red which is chromogenic substrate of thermotolerant coliform group galactosidase. Escherichia will turn blue on these count plates, and thermotolerant coliform will turn purple red or blue on them after culture at 44.5℃.

This product applies to rapid detection of Escherichia coliform and thermotolerant coliform bacteria of all kinds of water.

2. Using method

2.1 Regarding the positive result or producing acid and gas in the coliform group test, dip the coliform solution with inoculating loop, and blend with 2~3mL sterile phosphate buffer solution or normal saline. And then suck 1mL of the mixed solution onto E. coli & thermotolerant coliform bacteria count plate, cover the film gently and stand it for 10 second to let the medium solidify.

2.2 Place the count plate which is inoculated well back to ziplock bag and seal it well. Then put it in the incubator with transparent side up. And the quantity of superimposed count plates should not be more than 12. Culture the count plate at 44.5℃ for 15~24hs.

3. Results

Colonies of thermotolerant coliform would show purple red or blue on count plate, and those show blue are Escherichia coliform. There is not any purple red or blue spot if negative result. 

4. Additional information 

Thermotolerant coliform is part of total coliform group. If the temperature of incubator is up to 44-45℃, those can grow and ferment lactose are thermotolerant coliform. They contain some of Escherichia, Klebsiella, Enterobacter, Citrobacter rodentia. Among them, Escherichia is most accurate and exclusive indicator of feces. Compared with total coliform group, the fact that thermotolerant coliform is checked out shows the water sample is dirtier and the greater possibility of presence of intestinal pathogenic bacteria and food pathogens. 

5. Preservation condition

This kind of count plate should be stored in the fridge at 4℃-10℃, and the expiration time is one year. Once the package is opened, those unused count plates should be placed back to the package and then seal it well. Store them in the fridge and exhaust them within one month. Condensation may occur in high humid environment, it is better to warm it back to room temperature before unfolding the package.