I isolate LAB in MRS A + CaCO3 medium, but until now I cannot find the reason why a clear zone formed around the colony. I am wondering whether there are any researchers that can explain this question.
Thankyou @Ami R.Patel to answer my question. but at least i wanna know how is the mechanism to form that clear zone. i have to present my topic about this on Friday. so please tell me much references about this. i'm trying to open that link but it was broken :(
The clear zone is created due to disappearance of the turbidity originally created by the lower solubility of calcium carbonate. However, as the the lactic acid grows, they produce lactic acid that lower the pH and this in turn increases the solubility of calcium carbonate. Therefore, as the calcium carbonate dissolves that particular area becomes clear which indicates growth of the colony.
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