from what my doctor has told me, probiotics can be very acidic to the system, just as vitamins like C and B can be. If you are a doshic type that has alot of mucus naturally in the body, you can proobably handle this acid. Otherwise it can destroy the mucus lining of your organs, and damage the epithileal layer beyond, as there will be not mucus to protect the system from the acid.
I have a very non existant mucus level, and thus am supposed to eat a very basic boring diet...,pasta, white potatoes, white bread, white rice, no fruit, it is terrible, I love SPICY foods, and am not big on anything i just mentioned, so it is tricky, I get flare ups alot.

I'm not sure what the ph is of probiotics but If you drink some raw unfiltered apple cider vinegar it balances out the body's ph. If your body is too acidic it acts as alkaline if it's too alkaline it acts as acidic.