Just to let you guys know, I will probably be posting every Friday from now on, for the sake of having complete results.
 I decided to use a new concentration of dish soap for the biofilm tests that I did this week and that I'll carry out over the next couple of weeks. Instead of 10 mg/mL dish soap, the concentration will be 0.1 mg/mL. Here's why:
 Imagine you're washing a plate, by hand, with liquid detergent. You put one drop of soap on the plate and kind of swirl it around to get good coverage. Then you scrub, rinse, and dry. That drop of soap you put on the plate probably weighed about 0.1 g, or 100 mg. Now mix that with 10 mL of water, the water that you sipped at dinner or the water with which you washed the plate--that's a 10 mg/mL solution. But that's still an awfully large concentration of soap. If you ate off a plate coated in 10 mg/mL Dawn, you would probably taste more soap than food. So imagine that you rinse that plate REALLY well, how it should be rinsed. At this point, you can assume you've rinsed off the majority of the detergent, and thus 0.1 mg/mL of soap is probably a pretty good estimate of the maximum amount of dish soap you would eat off the plate, a hundred times less soap than you had before.

Now, this is the moment of truth.Science requires repetition.

When I walked into the lab Thursday morning and opened the incubator, I found that many of my plates had absolutely no bacteria growing on them at all. When I did my control enumerations, two of my three trial plates were completely empty. This didn't make sense, especially after following all the procedures and using a much smaller concentration of dish soap. But since there was no dish soap in my control row, the only logical explanation I could assign is that there was bleach in my test tubes that killed the bacteria, even though the tubes had been autoclaved. This being said, I will have to re-do my e.coli enumerations next week. But no biggie- I still have another six weeks or so, and three of those weeks have been set aside for this kind of thing.

My poor little plates...

I did the same biofilm challenge procedure with this new concentration, except I did one thing a little different. Instead of shaking off the detergent before sonicating the plate, I collected the detergents in test tubes and plated them using serial dilutions. This was done to determine whether the dish soaps penetrated sand killed bacteria inside the biofilm or simply swept them away. The detergent plates surprisingly grew more than my control plate, and still grew quiet a bit, which leads me to believe it's possible that the dish soaps are sweeping the biofilms away. However, this is unsure until I can get solid, unbleached data.

Detergent plates- top:Cascade, bottom: Dawn

But for now, I'm off to Oregon for spring break, so,
увидмся через две недели! (See you in two weeks!)

Mackenzie