as carried out for the bacteria, and the production of gas showed that they were catalase positive, eliminating Enterococcus faecalis as a possible result. After viewing the bacteria under a microscope, it was evident that they were coccus-shaped, not bacillus-shaped, which eliminated Bacillus subtilis as a possibility. One the MSA plate, the bacteria were surrounded by a yellow halo, indicating that it fermented mannitol, which led to the conclusion that the unknown Gram positive bacteria were Staphylococcus aureus. To further support this conclusion, the bacteria appeared off-white on the TSA plate, which matched the characteristics of Staphylococcus aureus in the Gram positive table.
It was concluded that the Gram negative unknown bacterium was Alcaligenes faecalis. First, the oxidase test was performed on the bacteria, and the bacteria were oxidase positive because the oxidase strip turned dark purple. This ruled out Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, and Serratia marcescens. The gelatinase test came out to be negative, and this led to the conclusion that the bacterium was Alcaligenes faecalis. To confirm this result, indole, urease, and motility tests were carried out. Results showed that the bacteria were indole negative and urease negative, which matched the characteristics of Alcaligenes faecalis. The motility test came out to be negative even though Alcaligenes faecalis is motility positive. This may have been the case because Alcaligenes faecalis is an obligate aerobe, so the bacteria in the SIM deep may have died due to a lack of oxygen, leading to no observable motility under the surface of the SIM deep. Aside from this test result, all of the other tests supported the conclusion that the Gram negative unknown bacterium was Alcaligenes faecalis.
Organismal Reports
Staphylococcus aureus is a Gram positive, coccus-shaped bacterium that forms grape-like clusters. It is a facultative anaerobe, beta-hemolytic, coagulase positive, and produces exotoxins. It is halophilic and can grow at a variety of temperatures.
The genus Staphylococcus has two major species: Staphylococcus aureus and Staphylococcus epidermidis. Unlike Staphylococcus aureus, Staphylococcus epidermidis is non-hem
