Top Posters
Since Sunday
31
28
10
10
10
9
9
a
3
3
2
J
1
New Topic  
Ari88 Ari88
wrote...
Posts: 19
Rep: 1 0
A month ago Edited: A month ago, Ari88
I did an experiment with tryptic soy agar medium recently and I had some issues so I need a few questions answered. The experiment was to use a TSA plate and first streak for isolation with yogurt in order to get a culture of Lactobacillus or Streptococcus. After incubating the first plate, we were asked to transfer 8 loopfuls to a second TSA plate. Next, we were asked to put a chloramphenicol disc in the center, a drop of isopropyl alcohol at the top, drop of milk at the bottom, bleach on the left, and finally hand sanitizer on the right. Because the plates had to be stored upside down, my chloramphenicol disc fell out. At some point, the chloramphenicol disc got stuck in the exact spot as the hand sanitizer. Now I don't know which one of those two things inhibited growth of the Lactobacillus/streptococcus. I later used sterilized forceps to remove the disc and re-insert it into the center, but I have no way of knowing if it ended affected to right side before it was removed.

So, in short, I need to know if hand sanitizer and chloramphenicol will both inhibit growth of those species or if only one or the other will. I will do some online research as well but I would like to verify what I find because there are often mixed and confusing answers online.

Thanks! :-)
Post Merge: A month ago

(also, I'm curious what affect chloramphenicol, milk, bleach, rubbing alcohol, and hand sanitizer will have on Saccharomyces cerevisiae and on Lactobacillus/Streptococcus thermopilus found in yogurt)?? They appear to have no affect on the yeast thus far but I'm unsure of my skills so I don't know how well I performed the labs.
Read 155 times
5 Replies
Replies
Answer accepted by topic starter
WooWoo
wrote...
Posts: 411
A month ago
Sign in or Sign up in seconds to unlock everything for free
Hand-sanitizer composed of alcohol will kill 99.9% of all bacteria - alcohol kills bacteria by damaging the cell walls.
1

Related Topics

wrote...
A month ago
What will a drop of milk do? Preliminary results do not show a difference between bleach, alcohol (isopropyl or alcohol-based hand sanitizer), chloramphenicol, or milk. This has be worried that I did something wrong as milk does not seem like it should have the same effect as isopropyl alcohol! :-) Confounded Face
Woo
wrote...
A month ago
Yup that is concerning. Milk in theory should make the culture grow. Milk has lactose in it, which is a carbohydrate, and carbohydrates are used as a source of energy
wrote...
A month ago
Thank you--that is good to know; I figured as much but I'm a new microbiology student so I thought maybe I was missing something! I know that some bacteria don't have the enzymes to digest milk so I thought maybe if it soured it would inhibit growth or something. Perhaps some of my bleach or hand sanitizer migrated down to the milk area :-)
Woo
wrote...
A month ago
Could have been when the disc dislodged.

Just bare in mind that there's no forgiveness when it comes to microbiology. One wrong move leads to catastrophic results
New Topic      
Explore
Post your homework questions and get free online help from our incredible volunteers
  167 People Browsing
 534 Signed Up Today
Your Opinion
Do you believe in global warming?
Votes: 310

Related Images
 205
 107
 100