Adaptive Radiation and Stress Physiology of Vibrio Fischeri

So far this summer I have been steadily collecting and gathering data on the growth of V. fischeri smooth morphs and wrinkly spreaders on a salinity gradient. To do this I have been growing bacteria on LBS growth media with different concentrations of sodium chloride and measuring OD600 with a spectrophotometer to determine the population density that V. fischeri is able to grow to over a period of 24 hours .

Setting up and running one of these growth experiments takes three days and I’ve been able to time my experiments so that I am able to collect a set of data every day. One of the main challenges of the project in the beginning was working out the timing of the experiments as well as deciding on an efficient amount of strains and salinity concentrations to do in each run of the experiment. For example, if I were to run and experiment with all the smooth morph and wrinkly spreader strains of bacteria at one salinity, that would equate to 130 test tubes of culture that all need to be individually inoculated from three-hour sub-cultures taken from 24-hour starter cultures and then measured individually with a spectrophotometer. I tried doing this in the beginning but it was too complicated and inefficient in terms of timing the experiments.

Instead, I first worked through all the smooth morphs at various levels of salinity and now I am working through the wrinkly spreaders.  This cuts the number of test tubes I’m working with down to 65 on any given day. Using a smaller number of strains of bacteria at once has made it easier to run experiments every day.