Science Buddies: "Ask an Expert"

I want to see how household pesticides effect bacteria growth in our lake. This is for my science fair. I am concerned that the cold will decrease the bacteria too much and my experiment won't have any clear results. I live in the south and we are just getting into some nights with freezing temperatures. I need to order my bacteria food and then I could complete the experiment. Any advice?
Tristan

Hi,

I would suggest collecting a supply of lake water. Use a portion of the lake water as a control, and make samples cpmtamomated by by your test materials. Keep a;; the samples at room temperatures for a day or two, then make agar plates streaKED WITH YOU CONTROL AND EACH OF YOUR TEST SAMPLES. Incubate the agar plates for a few days and count the colonies on each plate. I suspect this process will work just fine, as I doubt that your lakewater samples will be sterile, particularly after the water stands at room temperature for a day or two. If you want to be cautious, try holding your control lakewater a day or two at room temperature in sunlight, then streak and incubate an agar palete. If a reasonable number of colonies grow, then the experiment should work.

I am betting even if the baccteria counts are reduced in cold lake water, I would expect the counts to rebound if the water is warmed up and exposed to sunlingt.

Best regards,

Barrett L. Tomlinson