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Culture for microscope fun

  1. May 8, 2013 #1
    Hi, so I have a little background in biology. I took AP bio in HS and got a 5 and really enjoyed it along the way.

    I got a microscope for my own amusement and also to maybe spark an interest in my little brother.

    What I'm having trouble with is finding good densities of moving microorganisms. I though motile microorganisms would be the best place to start, because I've always found them to be the most mind blowing part of simple bio.

    I'm interesting in growing cultures in water to get some interesting stuff to look at, but first I want to inquire on the danger of doing so. I don't want to grow some deadly bacteria in my house.

    Also, if it is safe, what should I put in the water to aid in growth? Will normal cooking sugar work? Should it be in sunlight? And how long for optimal results? (Conceivably, after a certain period when density would peak, I'm guessing things will start dying.)
  2. jcsd
  3. May 8, 2013 #2


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    Staff: Mentor

    Form my young days - fistfull of a cut grass (or hay) in a glass of water should be a good start.
  4. May 8, 2013 #3

    Andy Resnick

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    You are only limited by your creativity: put some topsoil in water to let the microbes swim free; get some yeast from the grocery store and add water; find some stagnant water puddle outside; cut off that moldy spot on bread/cheese; etc. etc. Microbes are incredibly hardy and tolerant of a wide range of physical conditions.

    Tap water has a variety of chemicals added for safety- chlorine, fluoride, etc. that may kill the microbes. Use either rainwater/pond water/distilled water (from the grocery store). It may be helpful to add small amounts of sugar and salt, and don't worry about creating a 'superbug'- those appear when antibiotics are added to the culture.
  5. May 8, 2013 #4
    What you need is a pond and then you get pond water. You can make you own pond on a jar of small aquarium. You can go all out and buy an air pump and air stones. These create a vertical current and gas exchange. Or just use a a 1 qt mason jar.

    Simply add filtered water (no chorine) and then a small about of dry grass and soil. some small sticks and a bit of sand and dirt to make a 1/8 inch layer on the bottom. Place it in shade but still where some light hits. You do NOT want the sun to heat the water

    At first the water is nearly sterile but every day sample the dirt near the bottom with a tiny pipet and put a drop or two of the water and dirt on a slide, cover it and look at 100x or 400x.

    Note what you find. It will change over several weeks. Some populations will explode and soe will crash. no need to add nutrients. the decomposing grass and so on will add enough. In time you will see green algae which is a sign of a healthy eco system

    Air stones keep the system for becoming anaerobic. Nothing wrong there except it smalls bad. A thick layer of mud will grow anaerobic stuff too.

    When I did this at first I saw bacteria and it took a month before the water fleas appeared. They, I think are top of the food chain (???) and need food to multiply first. Later I see dead ones in the soil with smaller microbes feeding on the remains inside the shell.

    Make up two or more jars each with different stuff. Some from outdoors type samples, some with dirt from vacuum clearer bag. Get a thermometer and PH papers and record what's going on.

    This can't kill you unless you start to isolate and culture un-known critters. Then just be careful. But even with the open jars use gloves, wipe areas with alcohol. Drop all the used slides and beakers and pipets in the "to be cleaned" jar that has disinfectant solution (I just use a drop of dish soap) Months f bad or no cleaning will create a mess so treat the area like a real lab.
  6. May 8, 2013 #5
    Sounds like fun. My last final is Friday, so I'll start over the weekend. I like how this is a long term, evolving project with multiple aspects of biology involved. Not only the "ooo look cool little cell things" that I was originally intending, but also a good example of ecology. Thanks for the suggestions.
  7. May 9, 2013 #6


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    Yep, great idea.
  8. May 15, 2013 #7
    enough talk, you need to take pictures, so we can identify what you see
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