enzymes against bacteriocins

Mike Dew internul1 at hotmail.com
Tue Nov 21 11:30:36 EST 2000


Hi,

for a work on bacteriocin production from lactic acid bacteria, I use the 
deferred antagonism assay with good results. Many isolated strains (116 out 
of 1000) inhibit the target bacteria (Listeria) on solid media (BHI, TSA-YE, 
APT).
However, I cannot succeed to stop the inhibition by adding several 
proteolytic enzymes commonly used for this purpose.

The enzymes (protease, trypsine, proteinase K) are solubilized in PBS 0.01M 
at 10mg/mL, and a few ug are deposed on spots of lactic cultures on solid 
media, and an overlay is added containing Listeria. But the inhibition zones 
are still present. Obviously, maybe there are no bacteriocin-producing 
strains, but what can cause the inbition (clues: no peroxyde because 
anaerobiosis; no bacteriophages detected; no acidification because of the 
no-glucose TSA-YE) ? Is this enzyme methodology inadequate ?

Thank you for help !

Mike Dew
Center for aquatic innovation
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