IDENTIFICATION OF UNKNOWN BACTERIA: INSTRUCTIONS
PURPOSE: TO IDENTIFY UNKNOWN BACTERIA GIVEN A PURE LIQUID CULTURE
Worksheet:
1: STREAK PLATE OF UNKNOWN
- Assume here is a liquid culture that contains an unknown (the bacterium assigned to you).
- Pretend you have done a quadrant streak of your liquid culture to isolate individual colonies on four plates. Two NA (Nutrient Agar) plates and Two SDA plates. Be sure to review the technique in your lab manual before you proceed.
- These plates would incubate at 37ºC and at Room temperature after streaking.
- A gram stain using a culture of your bacteria would be done next.
*Explain the Gram reaction, size, shape and arrangement you would expect to see after performing these procedures of your bacteria.
2: RESULTS OF STREAK PLATE
- Streak Plate:
o The best plate out of the four plates (Growth and colony
isolation) would be stored in the refrigerator for future use.
*Draw what your streak plate would look like on your worksheet.
*Conclusion: What would a successful streak look like? What could be improved upon if you were to redo it after an unsuccessful attempt?
- Draw and color the gram stain result, the cells shape and arrangement.
OTHER TESTS:
During the Pathogenic Cocci and Enterics Labs you have learnt how to differentiate
between the various Genera of bacteria within each group. Depending on your results from your streak plate and Gram stain, you will have to figure out which test(s) to perform next to continue with the ID of your unknown.
UNKNOWN LAB REPORT:
- Cover sheet with instructor name.
- Worksheet completed
- Report should be typed using 1 ½ spacing and 12 point font and include:
o A title and purpose (what are you trying to accomplish?).
o Results and conclusions in a table for all tests performed during your
identification. Paragraph form will receive NO credit. Table purposefully large so there is extra room, but you don’t have to fill the entire thing.
o A written conclusion including a flow chart (dichotomous key) that CLEARLY shows how you arrived at the identification of your unknown.
