Can we identify e-coli in water?

I am trying to identify presence/absence of e-coli in a nearby pond. Is this possible to do with foldscope? I have the basic 140x-magnification version.

Over here is a video of the aquatic sample I took. although there’s a bunch of stuff “moving” around, all the movement is caused by my efforts to focus the lens and pan around. As I move the lens back and forth, the fluid within the cover slip sloshes around and a bunch of particles go up and down. But alas, I don’t see any animate movement by any particle — which would’ve been my aha moment — to actually see a bacteria move.

So back to my question: I was hoping to identify e-coli by seeing little particulate matter move on their own devices. How do (or can I even) get there? (In the video, at about 0:33 and later, I zoomed into what I hopefully thought was a colony of e-coli. Could someone confirm or deny my hypothesis.).

PS: Sorry that my lens is dirty. I couldn’t wipe clean the dried-up parker-pen blue ink stain on upper left no matter how hard I tried.

6 Comments Add yours

  1. laksiyer says:

    Hi @Jahnavi . Firstly Fantastic video for after long I saw a testate amoeba. At 0:33 , the structure that you see if of the shell of the testate amoeba. You might have seen it move if you focused on it for some time. To answer your question, you will be able to see bacteria in your foldscope. However, specifically recognizing E. coli is essentially impossible by microscopy, as many bacteria resemble E. coli in features. In a traditional microbiology setup, E. coli. is identified using specific biochemical tests or antibodies. However, you will be able to abundantly see bacteria, some of which might be related to Ec. Leave that pond water sample for a few more days in a bottle at home. I would also recommend that you try dark-field or angular illumination, as these are really tiny (Ec is 2 microns) For example see,

    Did you try soap and water to clean the lens? It is pretty tough. I would be careful using alcohol as it could affect the carrier material, but with care you could try that too.

  2. Jahnavi Keerthi says:

    Thank you for your swift, clear and detailed response. “Testate amoeba — now that’s a new concept for me! Also, I am now aware of the difficulties of trying to catch e-coli.
    I really appreciate you for taking the time to provide detailed answer to each of my questions!
    I will leave the pond water for a few more days and try an angular illumination. Same for cleaning the lens.
    Once again thank you for such practical tips. You must be a highly trained and experienced microbiologist. I am happy that Prof. Pakash has set up this web-site so that a novice like me can get guidance from an expert like you. Your help has greatly reduced the gradient of my learning curve!

  3. ezekieljakub says:

    Here is a suggestion. I find using liquid samples I use MUCH MUCH LESS than I would with a regular slide w. cover slip.

    Try using paper well slides. Cover one side with included tape… make sure edges are secure especially near well so you don’t leak. Press down tape down firmly with finger. NEXT use dropper and put a tiny bit … half the well … of liquid. Use less than you *think* looks right. NEXT with tape cut, cover top of slide again making sure to cover and tightly press edges. FINALLY use a glass slide -or- stacked paper slides to view.

    Practice this preparation method… it works great for me!

    Also to filter out larger particulates don’t forget you have microfilters with a delux kit.

  4. Jahnavi Keerthi says:

    Thanks Ezekiel Jakub for your suggestions. As mentioned, I put in a teensy droplet of water in a microwell, enveloped it in the provided clear adhesive, and looked at it. At first, no luck. Then I did phase contrast (thanks Laksiyer!) and lo and behold! Swimming critters! probably 1-2 microns wide!

    Check it out:

  5. laksiyer says:

    Brilliant! Did you try maximum digital zoom.

  6. Jahnavi Keerthi says:

    Thanks sir. I believe this was at maximum digital zoom. But I am not 100% sure. I will re-do, and see if I can increase zoom.

    PS: I have gone thru’ your other posts and they’re really awesome. Thanks so much for contributing to this website / blog.

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