Question from a student 20140420

Q
-----Original Message-----
From: EEEEEEEEEE
Sent: Sun 4/20/2014 11:59 AM
To: Prof. HS Kwan (School of Life Sciences)
Subject: Re: 2013R2-FNSC4180 : Food Microbiology: Mid-term grades have been sent to your email and is also attached here

Dear Professor Kwan,

Thank you for your reply.

I have encountered some problems when revising for the final examination. I will appreciate if you can help me in solving my enquiries during your free time.

(1) What is the purpose of 2% ethanol in controlling microbial growth? Is it that it may interfere the growth of bacteria but not yeast and mold? Then how about lactic acid bacteria?

(2) Under a growing environment suitable for growth of both Pseudomonas spp. and E.coli, Will Pseudomonas outgrows E.coli or in the other way round?

(3) Can S.cerevisiae grows under environment in which all criteria suitable for its growth but having low sugar?

(4) When choosing microorganisms preferentially grow on food, parasitic worm or protozoa should be eliminated because they need to grow with host but not in food. Is this statement correct?

(5) Pseudomonas spp. can grow under environment of low sugar, but can it grows on environment having low protein but moderate sugar? How about environment of low protein and low sugar? (Provided that all other conditions are suitable for its growth)

(6) In apple juice which is stored at 25 degree Celsius, which microorganism will more preferentially grows? Listeria monocytogenes or E.coli?

(7) Is L.monocytogenes a microaerophils or facultative anaerobes? We are given two different answers in mind-map and the table of lecture pdf.

Sorry for asking so many questions. Thank you for your time and looking forward to your reply.

A
Dear EEEEEEE,

Your questions seems to refer to questions from previous examinations. I cannot answer most of them because the questions have only partial information. Factors other than that you gave would contribute to the outcome and we need to look at them all.

Perhaps the only question that I can answer #4: parasitic worms or protozoa should not be able to grow in foods.

Also Listeria should be a facultative anaerobe.

Best,

HS Kwan