At our house, we've just finished Week 1 of our make-along project, a microbe biosphere (also known as a Winogradsky column). If you'd like to make one too, please join us, this is a longer-term project. Just read this post about collecting your ingredients, and this post about putting it all together.
Some quick notes.
Make sure your jar lid is on tight. The microbes are going to start producing a sulphur smell inside the jar that you won't notice at all if the lid is on right. Also, check your jar regularly and make sure the water level remains at least an inch or two below the top--if it appears to be rising, carefully take some water off the top and pour it down the toilet (and wash your hands).
Rising water should only be a problem if you use potting soil with vermiculite (those white, porous pebbles), which swells as it takes on water, causing the water to rise and seep from your jar.
Just a friendly suggestion.
Ingredient of the Week: Water
Speaking of water, each week I'll focus on a different ingredient in our microbe biosphere, and yes, this week, it's water.
Microbes are so small that their world is moisture, even if what we see is mud. Microbes in a dry environment (such as a desert) are dormant and waiting for rain. But why do microbes need water? Vitamins, minerals, and other nutrients dissolve in water. Tiny molecules of water bearing these nutrients enter our cells--and also enter bacteria--through holes in their bodies nearly as tiny as the molecules themselves. (The fancy name for this is osmosis.)
Why We're Making Microbe Biospheres
As I've said before, Winogradsky columns are self-sustaining and can last for many years. I've tried to track down the oldest in the world, so far without success, but I've read that some are over 20 years old. Some people consider them to be works of 'microbe art.' There are beautiful examples on permanent display at CosmoCaixa, a science museum in Barcelona (I'll post some photos if I can get permission).
That's all fine and well, but you might be wondering, what does this have to do with nature walks? How can this be interesting for younger kids? I've found some answers I thought I'd share.
While researching how to make our microbe biospheres, I stumbled upon a great resource for the amateur naturalist who is curious about microbes--A Field Guide to Bacteria by Betsey Dexter Dyer (check your libraries--ours had a copy!). Written specifically for amateurs, her introduction alone is quite inspiring. She was a professional biologist who had never found microbes to be particularly interesting, because she had thought no one who lacked a high-powered microscope would have any true ability to study microbes in nature.
Dyer will inspire you to see bacteria outside in nature, all around us.
Have you ever seen a burl on a tree? It's a type of huge growth, or gall, that's harvested by furniture makers. In a number of cases, the growth is caused by Agrobacterium that entered the wound. Or perhaps you've grown peas or beans. If you dig up the plant, you'll see some bumps on the roots (like these) which are a sign of Rhizobium, a bacteria that works with the plant to obtain nitrogen from the soil; when the plant dies, some nitrogen stays in the dirt (helping to fertilize other plants). Have you ever seen a shell on the beach that was covered in a green slime? Or a similar blue-black 'mold' on an old gravestone? You are likely looking at cynobacteria.
I hope you can see why we're so intrigued by growing microbes in our biospheres--they are everywhere, and knowing their "field marks" can help us recognize their presence at the beach, in our gardens, or on a nature walk.