Science Buddies: "Ask an Expert"

Hi, I'm currently preparing an experiment using the bacterial species vibrio fischeri to test the effects of different pollutants normally found in water on it. To measure these effects in a quantifiable manner, I was thinking of using a method of measuring the variation of my colonies bioluminescence over an interval of time. What would be the best way to do so? Any suggestions would be greatly appreciated. Thank you!

Hi,

First let me correct one technicality that I just noticed. Apparently the genus of Vibrio fischeri was changed to Aliivibrio in 2007, so you should use the correct genus name in your poster and report.

I found a project described on Instructables for making a bioluminescent 'light bulb' and water pollution detector (http://www.instructables.com/id/Biolumi ... r-Polluti/). Is that the procedure you are using? I read it and it has some interesting suggestions like making your own nutrient agar and isolating the glowing bacteria from fresh squid. It doesn't have much to say about using the glow to detect water pollutants, however.

If you google apps for measuring lux, lumens or light intensity, you can find several such apps for a smart phone. I have one that I use for measuring sunlight under a tree canopy, but I don't know if they are sensitive enough to measure bioluminescence. You should try it, though. Measuring your dependent variable, the light from your bacteria, with an actually numerical value is the best way to prove or disprove your hypothesis. With number values you can also do statistics on your data and that is the best way to handle it scientifically.

What pollutants are you going to test and at what concentration? Lead and mercury are harmful to most organisms, but nitrates and phosphates can sometimes make things like algae grow faster.

Let us know if you have more questions.

Sybee