Recently I received a letter from a Kombucha friend asking my opinion about freezing the Kombucha culture. I thawed one from last year and it took off like gangbusters - produced a great baby and good tea. Generally, quick-freezing microorganisms simply tenders them dormant but does not necessarily kill them. The kind of slow freezing we can accomplished in the freezer is most harmful to the majority of bacteria.
Ice crystals form and disrupt their cellular and molecular structure.
A small number of some types of bacteria may survive a year of freezing, others may have very few survivors. I do not know in detail how each one of the various microorganisms in K.T. react to freezing. When you thaw frozen K.T. and use it to start a new culture, at first it may seem that everything is fine. But chances are that you probably don't have the same K.T. as you started with. K.T. Some of them may have survived, others may have been damaged by the freezing process and died.