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Inoculating Water with Thermotolerant Coliforms?

Hi All,

I'm looking for advice on how to reliably inoculate water with thermotolerant coliforms (preferably E. coli), for the purpose of quality control testing the ceramic filters that my organisation, Abundant Water, makes and distributes across Laos for treating water.

I am specifically after a good starter culture (tried horse poo and nasty canal water already, not enough coliforms) to work with. Is there a commercially available starter culture available or if not which animals faeces would be the best starting point??

Many thanks!


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I am not sure why you are looking to test with coliforms other than by culturing at temperature you can evaluate. To get a starter culture that is calibrated and you know how many there are you probably need to look at bacteriophages. These are widely used in testing membrane and other filters and UV systems for validation purposes and cultures are commercially available. There is also a difference between validation testing for getting approval and QC testing of production samples. The former really needs to be done by an outside agency to have the validity and protocol required. Routine QC testing is a more in house activity but I would suggest does not need to involve bacteria. For safety reasons if nothing else try either using a dust of suitable size or even depending on the type of filter and the arrangement bubble point testing of a filter assembly using low pressure air on a wetted filter is quick cheap and effective and results are readily recorded.

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Hi Steve, thanks for your advice. In this case we are looking for routine QC testing but also may be used for new prototypes in some cases. Your suggestion of using low pressure air on the filters is interesting, we have tried pressure testing with mains water but not air yet, will look into it. We haven't looked at Bacteriophages for the simple reason that the labs over here cant test for it, do you know of any portable field labs (i.e. similar to DelAgua kits) which would test for Bacteriophages?

Woolyechidna gravatar imageWoolyechidna ( 2017-11-02 21:54:41 -0600 )edit

Are you sure you did your testing correctly? Water quality E.coli testing is so sensitive that normally there is no such thing as "not enough".

Although I could imagine the horse-poo was older and and mixed with urine (driving up pH and thus killing bacteria)?

In most cases I worked on we used fresh municipal waste water, but that might not be available in at your site. For animal poo I would look for as fresh as possible one... maybe chicken litter would work? With chicken you can easily keep a steady supply close at hand.

The commercially available E.coli cultures are probably not suitable for this, as they are typically not very environmentally resistant strains. Think of lab-rat vs. street rat.

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Thanks Krischan, re if we are testing correctly, the labs we have over here are underfunded and staff not well trained, so that is one possibility.

Woolyechidna gravatar imageWoolyechidna ( 2017-11-02 21:26:41 -0600 )edit

Also, after some research re horse poo, it turns out that it is relatively low in thermotolerant coliforms, as compared with other "domesticated" animals. Fresh municipal waste water is not an option at this site unfortunately.Re commercially available E.coli cultures, yes the samples would have to be analysed virtually immediately as I understand it, which is an issue with the labs in Laos. Thanks for your advice!

Woolyechidna gravatar imageWoolyechidna ( 2017-11-02 21:30:49 -0600 )edit
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