Each species has its own intestinal probiotics. Kombucha is optimal for people. Bees have different bacteria than we do in their intestines, and thus they would need their own "probiotic formulation".
I think it would be a waste of money. While it might not harm your bees, it is doubtful that kombucha/yeast will help them unless the yeast and bacteria match what are usually found in the bee's systems.
Google this and you'll get a list of known bacteria and yeast strains in bee intestines and ventriculus.
Christina
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