Unknown 413 Lab Report

Many steps were taken in order to narrow down and figure out which bacterium unknown 413 is. One of the first step taken in identifying unknown 413 was to do a gram stain. The gram stain, which was purple, resulted in gram-positive cocci. The gram-positive eliminated all the possibilities of unknown 413 being any gram-negative bacteria such as Escherichia coli, Enterococcus faecalis etc. The cocci morphology result eliminated any possibilities of it being any bacteria that are a rod. This left five different genera: Staphylococcus, Lactococcus, Micrococcus, and Enterococcus as a choice for the unknown.

Knowing that the unknown 413 is gram positive cocci the next step was to do some essential differential test. One of the first test done was temperature tolerance test. 6.5% NaCl and glucose broths were inoculated and incubated at different temperature. The results where that there was medium growth at 10℃ in the NaCl broth, this means that the bacteria can tolerate high concentration of salts and the 10℃ temperature. There was growth at 25℃ and 37℃ in the NaCl broth which confirms that the bacteria can tolerate high concentration of salt. However, there was no growth in the NaCl broth at 45℃, this could only mean that the organism cannot

be grown at this temperature however further teste were done to be certain. With the results for the glucose broth it is almost the same as the NaCl there was growth of the bacteria at 10℃, 25℃, and 37℃. This means that the bacteria can ferment glucose. Also, there was no growth in the glucose broth at 45℃. Further test where still needed in order to make the conclusion that the bacteria cannot be grow at 45℃ and above.
The next test done was to inoculate TSA slants and incubate each at different temperatures, this will conclude which temperatures the bacteria can tolerate. The result for the TSA slant at 10℃ was small amount of growth, which means that the bacteria can grow at this temperature. With the 37℃ slant there was heavy growth, this means that the bacteria favor this temperature. There was heavy growth in the 25℃ slants also, which means that the bacteria grown well at this temperature. There was no growth in the slant that was placed at 45℃, this concludes that the bacterial cannot be grown at 45℃ or above.
The next test done was on a differential media.

Mannitol Salt Agar contains mannitol, 7.5% sodium chloride and a pH indicator red. This medium allows the growth of salt tolerant organism. Salt tolerant organisms can tolerate the high salt concentration found in Mannitol Salt agar and thus they grow readily. If mannitol is fermented, the acid produced turns the phenol red pH indicator from red (alkaline) to yellow (acid production). Most Staphylococcus bacteria can be grown on the media, but they do not ferment mannitol in this case the medium will appear pink or remains red. Unknown 413 had growth on the MSA agar and bright yellow media and colonies were seen. This means that unknown 413 ferments mannitol and acid was

produce.
One of the next differential media used was Blood agar. Blood agar is one of the most commonly used media in a clinical lab. It consists of an enriched agar base (Tryptic Soy agar) and 5% sheep red blood cells. Some bacteria can produce an enzyme hemolysin. Hemolysin lyse red blood cells and degrade hemoglobin. The plate is used to identify bacteria that destroy red blood cells. There are three types of Hemolytic Activities: Beta-hemolysis refers to a clear zone around colonies this means that there was complete lysis of the red blood cells. Alpha hemolysis is indicated by greenish zones around colonies this is a partial hemolysis. Gamma-hemolysis no zones around colonies this means that blood is not hemolyzed. Unknown 413 on blood agar resulted in no zones around colonies, concluding that it shows beta hemolysis.