UV lights and Yogurt {Lab 12 - May 28, 2015}

     For this lab, we sterilized our broths using a UV steri-pen and also made some delicious homemade yoghurt!

UV Light Sterilization

     

     To test how effective the UV light was, we poured our broth along with our classmates' broth into a big beaker. We inoculated three agar plates (labeled B for before) with the broth before sterilization  We then took the UV light steri-pen and went to work sterilizing the remaining broth.

Killing the bacteria
. . . We hope!

Broth filled with all
of our unknown bacteria.

     After sterilizing the broth, we inoculated it in the three agar plates (labeled A for after). The six agar plates were then allowed to incubate overnight. The next day, the results were staggering. The before plates had colonies growing everywhere. The after plates didn't have any colonies! That goes to show you just how effective the UV radiation really is. 

Before inoculation and sterilization 

Before sterilization on right;
After sterilization on left

Before - left ; After - right

Before - left ; After - right

     This was a great test to do. We were able to see just how effective the UV light is against pathogens and bacterial growth. The UV light is beginning to be used more frequently in hospitals due to its effectiveness. This is important for us to understand the capabilities of UV lights so that they can become more widespread in their usage throughout hospitals.

Yogurt Making

      To make the yoghurt, we placed some milk in a large beaker and microwaved until it was boiling. After this, we had to let it cool down before inoculating bacteria. We let it cool so that the bacteria would not be killed when added. Once the milk had cooled down, we added a spoonful of plain greek yoghurt to the milk and stirred. The inoculated milk was then placed into a 37 degree incubator overnight.

37 degrees, the perfect
temp for making yogurt 

 

Yogurt Incubator

 

     The next day, we removed the yogurt and placed it in the refrigerator until we had finished most of our lab. Then at the end of lab, we got out the yogurt and tasted what we had made. Some of us thought it was slightly too buttery tasting, so we added some salt to it. 

Final thoughts:

     I thought it was really cool that we had made yogurt even if it tasted slightly different from what we are used to eating. 

Bon Appétit!