positive control for antagonism assay
internul1 at hotmail.com
Wed Sep 27 13:13:34 EST 2000
This will sound like a very basic question, anyway...
In an experiment to detect bacteriocin-producing bacteria against L.
monocytogenes, I am trying to make a positive control with nisin in an
(adapted) deferred antagonism assay, but I have a problem. Briefly the
-adding nisin (0,3 mg/mL, from Sigma 2.5% nisin) in a sterilised culture
supernatant (no proteolytic enzymes added);
-multiple pH adjustments from 4.8 to 7.1 in tubes to fit the best pH;
-2 uL spots on a TSA plate;
-thin overlay with BHI agar seeded with Listeria
-incubation at 30 deg C 24 h.
Result: no inhibition zones at all ! Listeria feels pretty good in the
overlay. But I have inhibition zones around the lactic acid bacteria
colonies cultured by the same method... What is wrong ?
Thank you for help ...
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.
Share information about yourself, create your own public profile at
More information about the Microbio