Microbiology lab report, unknown bacteria를 알아내는 방법에 대한 method, result, discussion 부분입니다.
To figure out which temperature the unknown bacteria would grow better, two plates were prepared after inoculating unknown bacteria. The plates were put into different temperature environments. The clear and abundant colonies would show the optimal temperature for the unknown bacteria. To figure out the morphology of the unknown bacteria, gram staining was processed, and EMB and PEA test plates were also used. The morphology was decided by shapes and colors in the gram staining, and motility in SIM medium.
The unknown bacteria (# 149) were Pseudomonas aeruginosa according to the results from tests. All observed results matched with expected results except optimal temperature test, gelatin test, Voges-Proskauer test, and H2S production test in SIM media.
Even though the expected optimal temperature was 37°C, the colonies were seen well on both 25°C and 37°C plates. The translucent colonies were very small and distributed well on both plates. That is because the temperature does not affect much on the growth of bacteria unless temperature is too low, around 4°C, or too high.
P. aeruginosa did not produce proteases, which means the bacteria were not able to grow in gelatin, while the expectation was producing proteases1. Because of technical error, the bacteria might not transfer into the gelatin tube, so it made an error in this test.
The color change in VP test means the organism ferments glucose to produce 2,3-butanediol. By Brown1
1. Brown, A.E. Benson’s Microbiological Applications, Short Version, 10th Ed. New York, NY:
2. Holt, J.G. Bergey’s Manual of Determinative Bacteriology, 9th Ed. Philadelphia, PA:
Lippincott Williams & Wilkins, 1994.
3. Todar, K. http://www.textbookofbacteriology.net/pseudomonas.html, 2005.
4. Alexander, S.K. and Strete, D., Eds. Microbiology: A Photographic Atlas for the Laboratory,
1st Ed. Houston, TX: Benjamin Cummings, 2000.