In: Biology
Create you own DICHOTOMOUS KEY showing which selective media and biochemical tests you would need if you were to test your unknown bacteria SALMONELLA ENTERICA. And also EXPLAIN the procedure on how you would use biochemical tests and selective media to ID the specific bacteria (Salmonella enterica).
Answer:
When we receive an unknown bacteria we start the process with a look at the gram reaction and morphology of the organism and arrangement of cells if of any significance. This also tells which culture media to use for isolating and differentiating this organism from other similar organisms. Motility is another test that will help eliminate some more organisms leading to presumptive identification. This will be followed by few biochemical tests which will in most cases suffice for the positive identification of the unknown culture.
Dichotomous key for unknown organism (Salmonella enterica) is as given below:
After the organism is confirmed or almost confirmed, it can be subcultured on a selective/ differential medium like Bismuth Sulphite Agar (BSA) or Salmonella-Shigella Agar (SSA) to further ascertain the growth characteristics.
BSA = Black colonies with metallic
sheen
SSA = Black centered colonies