Van Tran
Microbiology Tuesday 5:00
May 5, 2015
Unknown Sample # 7
1. Introduction: Using biochemical tests are a good way to identify unknown bacteria from a sample. It is basically a similar to a trial and error method, but rather than using trial and error a person would be using positive and negative results. Using biochemical tests will help a person identify certain characteristics of the unknown bacteria through a series of chemical tests. Of course more than one biochemical tests must be used in order to ascertain which specific bacteria that a person may have.
2. Biochemical Tests: One of the biochemical tests used involves a SIM tube. To do a SIM test first take an inoculating needle and sterilize it first and take some …show more content…
Sterilize an inoculating loop and obtain some bacteria and then inoculate it into the tube in a zig-zag motion from the bottom-up and then allow it to incubate. The Simmon’s citrate test is used to detect bacteria that use citrate as its carbon source. Inside the agar consists of sodium citrate as its carbon source and ammonium phosphate as its nitrogen source. If citrate is used then the bacteria will produce pyruvate which produces either acid or alkaline products. The test contains the indicator Bromthymol blue which is green at a pH of 6.9 and royal blue at 7.6. A positive result for citrate use is a royal blue color(Elliott, …show more content…
The one test that made the decision was the SIM tests. Due to S. typhimurium being the only bacteria that is negative for indole production and positive for both motility and sulfur was a major factor in determining that this was the unknown bacteria. At this point the other tests didn’t really matter, but for a greater certainty that this bacteria was indeed S. typhimurium the other tests were done as well. The lactose fermentation produced a negative result for acid and gas formation and the only other bacteria that showed a negative for both was Proteus vulgaris, but since that bacteria showed a positive result for indole this couldn’t be the bacteria. All the results have shown that this bacteria is indeed S. typhimurium as shown in the known results
Microbiology Tuesday 5:00
May 5, 2015
Unknown Sample # 7
1. Introduction: Using biochemical tests are a good way to identify unknown bacteria from a sample. It is basically a similar to a trial and error method, but rather than using trial and error a person would be using positive and negative results. Using biochemical tests will help a person identify certain characteristics of the unknown bacteria through a series of chemical tests. Of course more than one biochemical tests must be used in order to ascertain which specific bacteria that a person may have.
2. Biochemical Tests: One of the biochemical tests used involves a SIM tube. To do a SIM test first take an inoculating needle and sterilize it first and take some …show more content…
Sterilize an inoculating loop and obtain some bacteria and then inoculate it into the tube in a zig-zag motion from the bottom-up and then allow it to incubate. The Simmon’s citrate test is used to detect bacteria that use citrate as its carbon source. Inside the agar consists of sodium citrate as its carbon source and ammonium phosphate as its nitrogen source. If citrate is used then the bacteria will produce pyruvate which produces either acid or alkaline products. The test contains the indicator Bromthymol blue which is green at a pH of 6.9 and royal blue at 7.6. A positive result for citrate use is a royal blue color(Elliott, …show more content…
The one test that made the decision was the SIM tests. Due to S. typhimurium being the only bacteria that is negative for indole production and positive for both motility and sulfur was a major factor in determining that this was the unknown bacteria. At this point the other tests didn’t really matter, but for a greater certainty that this bacteria was indeed S. typhimurium the other tests were done as well. The lactose fermentation produced a negative result for acid and gas formation and the only other bacteria that showed a negative for both was Proteus vulgaris, but since that bacteria showed a positive result for indole this couldn’t be the bacteria. All the results have shown that this bacteria is indeed S. typhimurium as shown in the known results