Question from a student

From: LLLLLLLLLLLLLLL
Sent: Monday, 23 April 2018 9:43 PM
To: HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>; HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>
Subject: Questions about FNSC3180

 Dear Mr Kwan,

         I would like to ask a few questions considering the content of the exam.

1. Clostridium perfringens can survive upon addition of nitrate. Can it grow with addition of nitrate?

2. In past paper2016-2017 (A4), why is the answer not Salmonella Enterica?The redox -50 is suitable for its growth. For Clostridium perfringens, it should only survive but not grow in a salt con(9%too high). Actually, the Aw=0.9 is not suitable for growth of both Salmonella Enterica and Clostridium perfringens. Why is the answer Clostridium perfringens?Can you explain this question?

3. Is disease caused by Vibrio Cholerae an infection or an intoxication?

4. Why are germinating spores more sensitive than vegetative cells?It is the example provided when saying the precise limit for any given species depends on the physiological state of the cell. 

5. ''The most temperature-sensitive enzyme or process in a given cell will set the temperature limit for growth or survival under the given conditions.'' Does it mean that an enzyme which is with narrow temperature limit will set the temperature limit for microbial growth?

6. In the investigation exercise, does the question'' Can you hypothesize a scenario of what happened?'' mean that I have to state events that caused the outbreak in the answer?

         I look forward to receiving your reply on the blog. Thank you very much.

Dear LLLLLL,

Answers to your questions:

1.       No
2.       You are correct. Should be none. My mistake.
3.       Infection
4.       Germinating spores are more active physiologically. More active cells are more susceptible to environmental stress
5.       No, it means the enzyme with the lowest maximum temperature limit will set the temperature limit for growth and survival. One resumption is that the enzyme is an important enzyme.
6.       Yes
 

Best,

HS Kwan