I have some gram negative isolates that I had tested for Antimicrobial activity production and a lot of them were having antimicrobial activity but after subculture of these isolates, many of them had lost their antimicrobial activity.
Please help me if you have any explanation for that.
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The isolates were having antimicrobial activity against other bacteria but they losed this activity after subculture, Got it
I am not sure but perhaps there are some possible reasons. Have you checked if your isolates contain those genes? If bands still appear that perhaps something might be interfering with the expression or with the other post transcription process.
it is usual that strains loss antibiotic markers if the subculture is not with antibiotic, the loss of the plasmids is normal without a selective pressure
on repeated subculturing bacteria loses their special genes.
like repeated subculturing of virulent starin will convert into avirulent... as such genes could not express.
for such genes to get expressed u can subculture in a medium where ur bacteria can express those genes, hence active expressed and transfered to next generation.
Dear friend,
If your que is that your isolates with antimicrobial activity against other bacteria lost this activity after subculture??
As Mr. Bhim Thapa said earlier, there is possible that your cultures have lost the genes for expression of the antimicrobial agent or else, the antimicrobial molecule structure changed due to medium change.. Just check your initial conditions for the production of these molecules... Use the same strains from the plate which u had used initially (if viable!! for confirmation...)... lastly check for contamination in your stock of isolates (the last possiblility for a happy ending...)
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