Biological Media Lab Report

Lab Report 2
Biological Media
Meva Tinsley
Georgia State University

Lab Report 2
Introduction: Biological Media
Microorganisms require nutrients and certain environmental conditions in order to thrive. In the lab, we use a Biological Media to aid in growth reproduction. Also referred to as a culture medium, a Biological Media is a substance used to support the growth of microorganisms. The two types of media most commonly used in Microbiology are selective media and differential media. Selective media are used to encourage the growth of specific or desired microbes. Differential media on the other hand are used to distinguish colonies of microbes as well as identify different bacteria. When growing
I also sterilized the top of the test tube just for contamination purposes. Next I dipped my inoculation loop into the test tube to gather a sample of Staphylococcus aureus. Once I had my sample, I then began using the strike method to inoculate my TSA plate. I made sure to flame sterilize my loop between each strikes. I continued on using this same process to inoculate the three remaining TSA plates with the other three bacteria. After all of my TSA plates were inoculated with each bacteria, I move on to the second part of my experiment, which involved the EMB and MSA plates. My lab partner and I were required to take a marker and on the back of our EMB and MSA plates section each plate into four quarters. We then labeled each quadrant of both plates with one organism that we were given at the beginning of the lab. Next we labeled our plates with our names and lab times. We were then prepared to inoculate our plates. Starting with the EMB plate, I first sterilized my inoculation loop and dipped it into the test-tube. Gathering a light sample, I began to inoculate one quadrant of my EMB plate with a zigzag line. I made sure to start from the edge of the
I gathered all of my plates and tubes from the refrigerator and began my observation. At first glance, I noticed that TSA plate containing the bacteria Escherichia coli displayed the most colonies. The colonies were smaller and more clumped towards the edges. Towards the center of the TSA plates were larger colonies and they appeared to be a little bit more spread apart than the colonies around the edges. I counted about 38 larger colonies. Next I looked at the TSA plate containing the bacteria Pseudomonas aeruginosa. This TSA plate displayed larger colonies around the edges and in the center. The colonies were more attached which made counting the colonies a bit difficult; however I was able to count about 33 colonies. Following, I moved on to my next TSA plate, which had the bacteria Citrobacter freundii on it. This bacterium contained the largest colonies. The colonies were pretty close, and I was able to count about 25 colonies. The last TSA plate I examined contained the bacteria Staphylococcus aureus. This plate contained a lot of colonies however they were very tiny. It also contained about 10 larger colonies. After reviewing all of my TSA plates, I moved on to observe my MSA plate. Staphylococcus was the only bacteria that grew on my MSA plate. This bacterium was also the only one that changed colors. It became a neon yellow color while all of the other bacteria stayed a pink color. Next I moved on to my