A glimpse of the rotifers living in my hay infusion

Last month, I collected some pond water samples from my university and decided to make a simple hay infusion setup at home to see what microbes I can successfully culture. To make the hay infusion, I gathered some dried grass and dead leaves near the pond area (which we call “the lagoon”) and boiled them inside a glass jar. I then left the setup to cool down before filling the remaining volume of the jar with some of the pond water I collected. I check on the infusion every week and recorded the different microbes that would grow in it. For thoroughness, I tried as best as I could to identify each microbe and to note where in the setup I collected them (i.e., whether they were extracted from the top, middle, or bottom of the jar).

During the first two weeks, I observed that ciliates dominated my infusion, with some occasional rotifers and nematodes. But just a couple of days later, I noticed that the population of rotifers, especially bdelloids, boomed so much that they were already visible on the water surface. This piqued my interest so I decided to observe them more closely under the foldscope.

Most of the bdelloid rotifers that thrive in my infusion measure about 0.5 mm (500 μm) and thus are visible to the naked eye even when isolated. However, I also observed smaller bdelloids, and I’m not sure if they are the same species as the bigger ones. My best guess is that the predominant type is Philodina sp., though I would very much appreciate if someone could help me identify them more accurately, as I hope to culture them separately after a month. While at it, I’ll investigate further on why and how their population increased so suddenly and successfully.

I am also planning to feature the different cultures I have managed to establish from the same pond water samples in my next posts, so stay tuned! Currently, I call them my “micropets”. Foldscoping has really opened a lot of avenues for me to discover my passions, and right now I’m thinking of becoming a micro-breeder!

6 Comments Add yours

  1. MananSuri says:

    Wow. This is such a good post.
    Can a hay infusion be made at home? And if what are things that I should keep note of while doing so!! Really inspired by this post! 🙂

    1. Cedrick says:

      Hi! Yes, you can make a hay infusion at home. You’ll just need a glass jar or bottle, some dried grass or leaves (even leftover vegetables will do), and pond or aquarium water. If you don’t have the latter, spring or mineral water can be an alternative. Don’t use distilled or tap water! Before adding the pond water, add boiling water to the plant matter and let it cool. This will help enrich the water to speed up bacterial growth, which the microbes will later feed on.
      After several days, the water should turn brown and smell foul, and a scum may form on the surface, indicating the growth of bacteria. After about a week, the water should slightly clear up, which means that protozoa and other microbes are already multiplying. Just observe your setup every week. Here’s a nice guide I found for making a hay infusion, and it also mentioned the types of microbes you can expect to find as weeks go by: https://www.bodelin.com/proscope/wp-content/uploads/sites/3/2018/04/Microbes.pdf

      1. MananSuri says:

        Thank you so much for this! It’s so helpful for me 🙂

        1. MananSuri says:

          I’ve been trying to make a slide of the pond water sample I’ve collected, but making the slide has not been easy since the water doesnt stay in the tape, makes the cover slip slippery and at the end I am unable to make the slide. Can you share the techniques you used to make the slide. Would really appreciate the help 🙂

          1. Cedrick says:

            Oh, I see. I’ve been using a concave slide. It’s a type of microscope slide with a concave-shaped depression or well at the center so it can hold a tiny drop of liquid sample for observation. I think you can also use the paper slides with holes that came with the foldscope for the similar purpose, just put a tape on one side of the holes, then drop a small amount of sample on each hole, and then cover them with another tape. The holes will serve as the “wells” on the paper slide. You could try this method, though I haven’t tried it myself, or you could just look for a concave slide. It looks like this: https://www.ebay.com/itm/Microscope-Cavity-Well-Concave-Slides-Pack-of-5-in-Mailer-Case-/152912894160

  2. MananSuri says:

    I now have access to cavity slides through my school’s lab. Can’t wait to do some explorations!

    Thank you so much 🙂

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