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Lab Report Identifying Unknown Microorganisms

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In this experiment, we cultivated an unknown specimen containing two microorganisms. The purpose of this experiment was to use a variety of biochemical test previously learned in the lab to identify the unknown bacteria. The identification of unknown bacteria is a major part of microbiology. Microbiologist observe samples such as blood and sputum in the laboratory for the presence of microorganisms. Identifying unknown bacteria is extremely important in clinical settings because it helps physicians find treatment for infections. I expect to learn the biochemical differences in bacteria from this lab. Also, how to identify different species of bacteria. Material & Methods For the first day of the practical, an unknown specimen was provided …show more content…

Mannitol Salt Agar: No growth occurred on this plate. Justification: Proteus vulgaris produces Hydrogen sulfide. The unknown organism produced Hydrogen sulfide in both the SIM Agar and TSI Agar. Proteus vulgaris is a motile microorganism that produces Indole. In the SIM Agar, the unknown microorganism was motile and produced Indole. Identification: Staphylococcus epidermis Justification: Staphylococcus epidermis is glucose fermenter. The unknown organism fermented glucose in the Phenol Red Glucose broth. Staphylococcus epidermis produces the enzyme catalase. In the PEA Agar, a catalase test was performed which showed that the organism produced catalase. Staphylococcus epidermis is not a mannitol fermenter. Mannitol fermenting organisms grow on the Mannitol Salt Agar. The unknown organism is not a mannitol fermenter because it did not grow on the Mannitol Salt Agar. Interpretation NA plate: The NA plate had growth of both organism even though it was difficult to differentiate between the colonies on this …show more content…

The organism fermented the sugar producing an acid which caused the phenol red pH indicator in the broth to become yellow. Phenol red is red in basic conditions and yellow in acidic conditions. Under oxygen limiting conditions, some organisms utilize sulfur compounds as terminal election acceptors (lab manual). The byproduct of this reaction is hydrogen sulfide. The medium contains iron salt which binds with hydrogen sulfide to produce a black color. The organism inoculated in this slant produced hydrogen sulfide because the butt of the slant was

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