Prepping for Yogurt Cultures: The Results are In

After five consecutive days in the incubator, our dilution samples had time to grow and now we are able to report our findings.

Results: The petri dishes were covered in bacterial colonies. Each of them grew bacteria, but in some of the dishes the colonies were not visible to the human eye. The higher the dilution factor, the more visible the colonies were.

Reika's results

Theresa's results

Nadine's results

Discussion: The purpose of this experiment was to do a trial dilution experiment so that we will have the necessary skills to dilute our yogurt and kefir when it comes time to count our bacteria. Before we could even start counting the colonies, we had to dilute each the amount of bacteria in the media. The dilution factors increased as follows: 101, 102, 103, 104, 105, and 106. After the bacteria were placed in the incubator for five days, we were able to draw conclusions about the amount of bacteria just based on what we saw. The lower dilution factors (101, 102, 103, 104) contained more bacteria within their petri dishes; however, they were more difficult to count just by looking at them. The higher dilutions contained more bacterial colonies but they were easier to count. The 106 petri dish was big enough to actually count the exact amount of colonies that grew.