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EFFECTS OF SHAKING WITHOUT AERATION ON ESCHERICHIA COLI GROWN IN LIQUID MEDIA.  Rachel N. Edes¹, E.A. Juergensmeyer², M.A. Juergensmeyer³, and E.S. Nelson⁴. ¹ Illinois Math and Science Academy, Aurora, IL, ² Judson College, Elgin, IL, ³ IIT Research Institute, Chicago, IL, and ⁴ NASA Glenn Research Center, Cleveland, OH.

   A common practice when growing aerobic bacterial cultures is to place liquid media on a shaker, with the assumption that shaking increases the amount of dissolved oxygen in the media. Space-flown cultures, however, are exposed to shaking in the form of vibration, without the increased exposure to air. We have investigated the effects of aeration vs. shaking without increased aeration to determine whether or not shaking alone can affect the growth rate of bacteria in liquid media. We have compared the growth of Escherichia coli with and without shaking in flasks (exposed
to air), test tubes (with and without exposure to air) and syringes (no exposure to air).  Shaking without aeration affects the growth curve of  E. coli.  Failure to consider the effects of vibration on space flight experiments can lead to the attribution of effects to microgravity which are due to other causes.

(Supported by NASA grant NAG2-1512)