Exercise 14 Unknown Identification Lab Report

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Exercise 14: Unknown Identification Lab Report The purpose of the study was to identify the unknown bacterium using various biochemical tests in addition to using scientific methods in determining the outcome of the hypothesis. Each biochemical test will help determine the bacteria based on specific characteristics of each organism. I was giving unknown number 232. The first procedure that needed to be done after obtaining unknown bacterial mixture was to isolate the two bacteria in a pure culture using the streak plate method described in Microbiology Laboratory Manual Eight Edition. The material used was trypticase soy agar (TSA) plate, nutrient plate, starch agar, hydrogen peroxide, iodine reagent and microscope. In order to obtain pure …show more content…

The TSA unknown organism B appearance was circular and yellow in color and slightly convex on the TSA plate. Organism A appearance was circular and seemed slightly raise on the TSA plate. On the first attempt I was not able to locate either organism at 100X lens so I had to preform a second steak plate and incubation time period. I was again able to isolate two separate colonies. Streak isolation on a nutrient plate agar was performed using ½ of organism from the original TSA plate where the colonies were isolated. The second ½ of the organism was used for gram staining. The gram stain method was performed on the unknown organism per lab manual page 42 and two gram stain reactions were identified. Organism B was gram positive cocci in grape like clusters. Because organism B was positive I could eliminate Escherichia coli, Enterobacter aerogenes and Proteus vulgaris because these bacteria would be rod shapes. Organism A was gram negative pink rod shaped and because of gram positive morphology I could eliminate Staphylococcus aureus, Streptococcus lactis and Bacillus subtilis. Since unknown organism B was gram positive, I had decided my first biochemical test would be the Catalase test per lab manual. The result of the catalase test after adding H2O2 was immediate air bubbles. The second biochemical test performed on organism B was starch agar per lab manual. Once the reagent was added I did not

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