29 November, 1999
Science in the Kitchen
As you know from reading the description of the research near the top of my web page, one component of the research at Lake Bonney is to culture the organisms we are pulling out of the lake in our water column samples. If you can get them to grow, you can control the amount of organisms you have to use in further experiments. Given the right temperature, light and nutrient conditions that simulate their natural environment, you can keep cultures around for a long time, even years.
To grow bacteria, viruses and phytoplankton, you need to come up with the perfect, nutritious "meal" for the organisms to feed on. This is called the "culture medium". The right medium provides an environment that stimulates these one-celled organisms to reproduce by cell division. Once they start dividing, each half divides again and before you know it, you've gone from one cell to thousands. This is exactly what the two Johns and Jack want. Lots of new cells. But first, they've got to find the recipe for that perfect medium.
Like making any new recipe and serving it to a large family of finicky eaters, you never know for sure who's going to like what. If you really want your family to eat, you may end up deciding to prepare a smorgasbord so everyone can pick and choose their favorite. Of course, making so many types of food for one meal would get tiring, fast. Fortunately, unlike phytoplankton, picky family members can make their own meals if they don't like what's being served.
Well, mixing culture medium is sort of like trying to please that difficult family. Not only are you searching for the perfect meal full of all the right ingredients, you hope the meal will be palatable. The organisms have got to want to eat, or you'll end up disappointed, with a petri dish of dehydrating agar and some miniscule dying cells languishing on the surface.
John L. and Barb have been making batches of powdered culture medium in the tiny 6'x 10' lab next to the Jamesway. Since the recipes tend to make huge batches of medium, and they only needed a fraction of the amount, they had to re-calculate everything using complex algebraic formulas. This was very time consuming. Once they had their new proportions, they were ready to get into the chemicals. When the powders were thoroughly mixed, they added de-ionized water to make a liquid medium. They put the jars of medium in the pressure cooker and steamed them sterile. By the time they were done, they had a number of different recipes to try the organisms out on. They'll feast the same type of organisms on a variety of media. It'll be the big phytoplankton "taste test" to see which they prefer.
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