Appendix B: Identifying Bacteria Identification
University of Phoenix Material
Appendix B – Identifying Bacteria
Bacteria identification is accomplished in a number of ways. Two common tools microbiologists use to identify unknown bacteria include dichotomous key and biochemical tests. The dichotomous key is useful when a microbiologist only needs to know which group an unknown microbe belongs to on a general level. When a microbiologist needs to identify a specific bacterium, biochemical tests are used.
PART ONE: GENERAL BACTERIA IDENTIFICATION
Review the dichotomous key in Figure A, the bacterial shapes in Figure B, and the Gram stain information below. You will use all three to determine to which major group unknown bacteria belong.
Gram Stain Results:
Purple = Gram positive
Red = Gram negative
Neither purple nor red = No cell wall (neither Gram positive nor Gram negative)
Review Figure C on the following page. Use Figure C to identify the type of arrangement displayed by the unknown bacteria. Read through the Sample Identification on the following page for an example of how to identify bacterial groups and arrangements using Figures A, B, C, and the Gram stain results.
Sample Identification
After performing a Gram stain, you observe the following under a microscope:
(Cells are stained red.)
Begin with item 1 on the dichotomous key …show more content…
One possible source of contamination may be the produce that is grown and distributed locally at a farmer’s market. A test sample of some of the produce revealed evidence of bacterial contamination. The bacteria sample was tested in a microbiology lab and showed the results that follow. The laboratory also performed a Gram stain of the isolated bacteria and ran a number of biochemical tests to aid identification. The biochemical tests were assayed using the Analytical Profile Index (API) 20E system for identification of Enterobacteriaceae and other gram-negative
Appendix B – Identifying Bacteria
Bacteria identification is accomplished in a number of ways. Two common tools microbiologists use to identify unknown bacteria include dichotomous key and biochemical tests. The dichotomous key is useful when a microbiologist only needs to know which group an unknown microbe belongs to on a general level. When a microbiologist needs to identify a specific bacterium, biochemical tests are used.
PART ONE: GENERAL BACTERIA IDENTIFICATION
Review the dichotomous key in Figure A, the bacterial shapes in Figure B, and the Gram stain information below. You will use all three to determine to which major group unknown bacteria belong.
Gram Stain Results:
Purple = Gram positive
Red = Gram negative
Neither purple nor red = No cell wall (neither Gram positive nor Gram negative)
Review Figure C on the following page. Use Figure C to identify the type of arrangement displayed by the unknown bacteria. Read through the Sample Identification on the following page for an example of how to identify bacterial groups and arrangements using Figures A, B, C, and the Gram stain results.
Sample Identification
After performing a Gram stain, you observe the following under a microscope:
(Cells are stained red.)
Begin with item 1 on the dichotomous key …show more content…
One possible source of contamination may be the produce that is grown and distributed locally at a farmer’s market. A test sample of some of the produce revealed evidence of bacterial contamination. The bacteria sample was tested in a microbiology lab and showed the results that follow. The laboratory also performed a Gram stain of the isolated bacteria and ran a number of biochemical tests to aid identification. The biochemical tests were assayed using the Analytical Profile Index (API) 20E system for identification of Enterobacteriaceae and other gram-negative