Article Summary: Yes, automatic dishwashers do kill bacteria present on dirty dishes! This page presents some simple 中国福利彩票下载安装αpp microbiology experiments that you中国福利彩票下载安装αpp can do to investigate the effectiveness of various ways of cleaning dishes. See the results of our own experiment at the bottom of this page.
Does the Dishwasher Really Sanitize Dishes?
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There are many different interesting questions you中国福利彩票下载安装αpp can investigate with the supplies listed in this article. A few examples:
How well do you中国福利彩票下载安装αppr household cleaners work to eliminate bacteria? Obtain a sample from an area before and after cleaning.
How clean are you中国福利彩票下载安装αppr childrens' toys?
Does hand washing work better than hand sanitizer?
3. Label the bottom half of the Petri dish, the side that contains the media. Draw a line down the center of the Petri dish bottom. Write "dirty" on one side of the line and "clean on the other. Also include you中国福利彩票下载安装αppr name, date and how long the dirty dishes have been sitting in the dish washer.
4. Carefully remove sterile swab from packaging. Be sure not to let it touch anything.
5. Open the dishwasher containing dirty dishes, and run the swab over the dishes and the inside surface of the dishwasher.
6. Lift the top off the Petri dish without setting it down (This could contaminate).
7. Take the swab and very gently run it over the surface of the TSY on the side marked "dirty". Use a tight back-and-forth pattern to make sure the swab contacts most of the agar on that side of the plate. Be careful not to touch the "clean" side.
for less than $30, with most everything you中国福利彩票下载安装αpp need, but the kit does require that you中国福利彩票下载安装αpp pour the media into the Petri dishes. To do this, you中国福利彩票下载安装αpp must use aseptic technique to avoid contaminating the media. See the video to the left for a demonstration of how to aseptically pour agar and follow the instructions supplied by the company you中国福利彩票下载安装αpp buy you中国福利彩票下载安装αppr supplies from.
Experimental Procedure for Dishwasher
1. If you中国福利彩票下载安装αpp need to pour you中国福利彩票下载安装αppr TSY media into Petri dishes (also called "plates"), do that first, with safety goggles on. Watch the video to the left and follow manufacturers instructions. If you中国福利彩票下载安装αpp are able to purchase pre-poured plates, skip steps 1 & 2.
2. Wait for the media to cool and become solid (like Jello).
How to Pour TSY Media Into Petri Dishes
(Put you中国福利彩票下载安装αppr goggles on first!)
Both of these plates and the one pictured above in the procedure instructions were taken from the same dishwasher run with hot water and heated dry. Two of the three plate have no bacterial growth. The plate with bacterial growth was prepared by budding 6-year-old scientist, so the growth on the "clean" side may have resulted from contamination or technique.
The plate to the left was prepared on a different occasion. Dishes had been sitting in the dishwasher for 24 hours before the cycle ran, hot wash and air dry with no heat.