For surface contact method to count the bacteria number of phone surface. Use a
ID: 141792 • Letter: F
Question
For surface contact method to count the bacteria number of phone surface. Use a sterile swab touch phone and put swab into tube which has 4ml dilution water in it. Agitate the tube and distribute 0.3 each solution into 3 empty plates and 0.1ml each solution into another 2 plates. The results of count are 27 CFU/g and 64 CFU/g respectively for the same object count. Explain the reason why these 2 values differ greatly. Also give drawback and benefit of this method. For surface contact method to count the bacteria number of phone surface. Use a sterile swab touch phone and put swab into tube which has 4ml dilution water in it. Agitate the tube and distribute 0.3 each solution into 3 empty plates and 0.1ml each solution into another 2 plates. The results of count are 27 CFU/g and 64 CFU/g respectively for the same object count. Explain the reason why these 2 values differ greatly. Also give drawback and benefit of this method.Explanation / Answer
This two value differ due to different concentration use by the researcher in first they use 0.3ml and in second they use 0.1ml of solution as the dilution rate increase value of colony count decrease this is one of the reason other reason can be plating error which is due to improper spreading of solution lead to difference in CFU.
Pros- This technique is quite fast
Can be used for any bacterial strain
Cheap and economical
Cons- High chance of error rate while counting plate
Time management is very important if you forget to observe the plate on time colony count can vary.