Essay On Biochemical Test

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In medical or science field, biochemical test are used to identify unknown bacteria. In this case three test are essential to identify the unknown #63 and they are MAC agar test, BCP (lactose) broth and SIM deep medium/slant. Methods such as streak plate technique, aseptic technique, and proper handling of the microbe are necessary to apply when conducting these biochemical test. Contamination during the unknown lab project shows carelessness and may put patient in jeopardy due to incorrect result(80). The MAC agar plate that was stored in the incubator at 37°C for about 48 hours until the next lab time presented colonies in a dark red/pink color hinted that the microbe is a lactose fermenter(117). After 48 hours of incubation at a 37°C, BCP …show more content…
This procedure is done once a week and stored at a 24°C incubator after 24-48 hours of initial growth. After transfer is completed, student can begin working on their first step of biochemical testing.
The first procedure in the biochemical tests of enteric bacteria was to use a bunsen burner to sterilize the inoculation loop then streak unknown bacteria on to the MAC agar plate using streak plate technique referred from the lab manual in exercise 7. The MAC agar plate was then stored in the incubator at 37°C for about 48 hours until the next lab time.
The second procedure in the biochemical tests of enteric bacteria was to inoculate the unknown bacteria into the BromoCresol Purple (lactose) broth using an inoculation loop, but before that the inoculation loop was placed above the flame to be sterilized. It is very crucial that aseptic technique is applied to prevent contamination therefore, bunsen burner is always used to sterilize the inoculation loop or the inoculation needle. The inoculated BCP (lactose) was then stored at a 37°C incubator for 48 hours until the next lab
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The result indicated that the unknown #63 was positive for lactose fermentation and eliminated S. marcescens, P. mirabilis, and P. vulgaris, which are lactose nonfermenters. BCP (lactose) broth which was originally a purple colored medium turned into a color yellow and signs of gas production was also noted. The result indicated that the unknown #63 was positive for both acid and gas production and eliminated K. pneumoniae, and E. aerogenes because they can produce acid, but no gas production was suggested from the dichotomous key. The test result for SIM deep slant that was used to test for sulfur-reducing turned up positive due to its color changed into a blackening color. The test result eliminated P. aeruginosa and identified unknown #63 as being Citrobacter freundii. During the unknown lab project, I was quite thankful that there were no mishaps in my lab work. There were no contamination, spills or accidents. The only problem I had during this project was the BCP (lactose) broth that was quite hard to tell if there was gas production. The enterotube test confirmed that my unknown #63 produced gas because a pocket of bubbles appeared in the

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