Marvelous mud microbes!

posted Aug 30, 2010, 12:46 AM by Beth Orcutt
Greetings microbe adopters! As the scientists start the final week of Expedition 327, we (sadly) bring this edition of the Adopt A Microbe project to the last activity. Luckily, though, this activity will keep you entertained with delightful microbes for a few weeks…and maybe by then a new Adopt A Microbe project will have started :) 

Out here on the Juan de Fuca, the final CORK experiment of Expedition 327 has been installed at the seafloor. For the final week of the expedition, the scientists will be up to their elbows (maybe even up to their eyeballs!) in sticky mud from a new site that we affectionately call “Grizzly Bare”. Grizzly Bare is a ‘bare’ hill of rock poking out of the mud at the seafloor. The scientists think this is a place in the ocean where seawater is being pulled into the oceanic crust, part of the process of hydrothermal circulation (remember that hot water superhighway we mentioned earlier?). The scientists plan to poke some holes in the mud around this little rocky hill to test if their hypothesis is correct. 

As you might imagine, the microbiologists on the ship are very excited to be collecting mud (and maybe some buried rocks) from the bottom of the ocean – think of all of the microbes they might find! In honor of all of the mud microbes, for this week’s activity, we will all set up experiments to examine mud microbes. The plan for this week is to set-up world-renowned ‘Winogradsky Columns”! 

What is a Winogradsky Column, you wonder? Well, it is an experiment named after a clever guy - Mr. Sergei Winogradsky – who was interested in studying soil microbes about a century ago. He came up with the slick idea of incubating soil and mud with some yummy carbon and sulfur sources to see how the microbes would respond. What results after a few weeks of incubation is a beautiful mixed community of microbes living together, including pretty purple, green, and white bacteria. 

In the experiment, mud from the banks of a stream, river or lake is mixed with some shredded newspaper (the carbon source, in the form of cellulose) and the yolks of hard-boiled eggs (the sulfur source – which is why rotten eggs smell so bad) and then placed in a tall and skinny container with a little bit of water on top. Over time, the microbes will eat up a lot of the oxygen in the mud, and the bottom of the container will become “anoxic” or oxygen free. Since the top of the container is open, oxygen can still seep into the upper parts of the container. Depending on their need for oxygen and the other food in the mud, different microbes will begin to dominate different depths in the container. You will be able to see this separation over time (3-6 weeks) as the microbes start to grow really thick into bands of different colors. 

Ready to get started growing your own mud microbes?! 

Things you will need: 
2 empty plastic water bottles, half-liter size 
a bucket or bowl to collect mud into 
a hand-shovel or large spoon to scoop mud with 
plastic wrap 
rubber band 
the yolk of a hard boiled egg 
a handful of shredded newspaper 
a well-lit spot where you can leave the container for a few weeks (but not in direct sunlight) 

Step 1: 
First, watch this great 5-minute video made by NASA Quest that will give you an overview of setting up your own Winogradksy column.  

Step 2: 
Take the bucket, spoon/shovel and one of the plastic bottles to the bank of a nearby stream, river or lake. Taking care not to fall into the water or get stuck in the mud, scoop up a few handfuls of mud into your bucket. Try to avoid mud with lots of roots or rocks. 

Step 3: 
Fill up one of the plastic bottles with water from the stream, river or lake. Close up the bottle and bring it and the mud bucket back home. 

Step 4: 
Cut the sloped top off of the other empty water bottle, so that you end up with a tall and skinny open container. You can invert the cut-off top as a funnel for filling the container, if you want. 

Step 5: 
Add a handful or so of the shredded newspaper and the yolk of a hard-boiled egg to your mud bucket and mix it up with the spoon. You want the mud to have the consistency of a milkshake, so if you need more water, use the water you collected (but don’t use it all, you will need a little bit for the end). 

Step 6: 
Carefully add the mud mixture to the container, tapping it on a flat surface to squish out any trapped air bubbles. Fill the container two-thirds to three-quarters of the way up. 

Step 7: 
Pour a little bit of the water on top of the mud in the container, leaving about half an inch or space between the water and the top of the container. 

Step 8: 
Place a piece of plastic wrap over the container top and hold it in place with a rubber band. 

Step 9: 
Now your Winogradksy column is ready to start incubating. Store it somewhere in a well-lit room, but not in direct sunlight. Check on your column every week or so for 3-6 weeks to see what develops. If you want, take pictures of your column every week and send the results by email (we’ll keep checking our email even though the Adopt A Microbe project of Expedition 327 is ending). 

We hope that you have tons of fun watching your mud microbes grow over the next few weeks! We have had tons of fun hosting the Adopt A Microbe project and interacting with you all – thanks for adopting some microbes! There will be a few more updates and stories from Mario the Marinobacter on the website over the next few days before Expedition 327 ends, so stay tuned! 

In case you are curious about the different microbes that start growing in your Winogradsky Column, check out this great website that gives lots of details. 

And now, we have some questions for you, dear microbe adopters. If you have a few minutes to spare, we would really appreciate it if you could fill out our online survey about your experience with the Adopt A Microbe project. If you fill out the survey, you’ll be entered into a contest for spiffy prizes! 

Many thanks!