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 …show more content…

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