UV Lights & Yogurt

In lab today we used UV light as a means to kill bacteria and we also cultivated our own pro-biotic yogurt!

To start things off we made a streak of bacteria 'L' and placed it under a UV light. We covered have of the plate as a control to observe if the bacteria was killed or not. We also removed the glass lid so that the UV rays did not refract off the glass. The UV light was left on the bacteria for 30 seconds. After decent exposure, we placed the sample in the incubator. If after 48 hours the bacteria does not grow on the half of the plate that was exposed than we know the UV method worked on bacteria 'L'!

Semi-covered bacteria streaks being exposed to UV light

We also used a Light Purifier in water to kill bacteria and obtain drinkable water. Our professor speaks highly of this purifier because it uses UV light to kill the bacteria in a glass of water. Dr. P uses this often when he is traveling in India and says that since using it he has not gotten sick nor experience traveler's diarrhea. To test this purifier we used the aseptic technique to transfer to of the student's bacterias into the water. While the UV light in the purifier was on, we mixed the water in order to increase maximal contact between the light and bacteria. Once finished we then sterilized the purifier with rubbing alcohol & the flame from a Bunsen burner. We than created a streak plate, incubated it and will return next lab to determine if the purifier worked.

UV light in the Purifier as it elimates bacteria in the water

Making Pro-biotic Yogurt!

We first took Full Fat Vitamin D Milk and heated it up in the microwave until it boiled. Once it came out, we waited until it cooled to 37 degrees Celsius. (Dr. P sped up the process by using cool barrister skills to pour the milk into cups and back into the bowl). We then separated the milk into three cups. The first cup became the control and was only Vitamin D milk. The second milk cup was mixed with a crushed pro-biotic tablet and the third was mixed with Kefir (a pro-biotic drink). The samples were than placed in the incubator and we will check next lab for growth of healthy pro-biotics in the milk. This growth will also lead to the formation of yogurt from the milk!

Vitamin D milk being poured into a bowl to microwave

Crushed Pro-biotic Tablet

Until then,

Annie B