Can probiotics acidify soil?

[Lycopersica]

I've been using rock phosphate with probiotics as a soil amendment. However, it seems to cause some sort of root stress when ever I use it on top of the soil. I applied it during my recent bout with blossom end rot. Afterwards, the mulch got a white crust and the plants struggled to get enough water. I had to start watering them every day and, even then, the new growth would wilt slightly on hot, sunny days.

Thankfully, the plants bounced back after I removed the discolored mulch and gave them extra water for a couple weeks. I'm still scratching my head as to what exactly went wrong though. At first, I thought I overfed them but I haven't had any problems with plant food or other amendments. The only thing I can think of is the probiotic. Could the bacteria be overpopulating and producing a lot of acid? And would an increase in soil acidity make it harder for roots to take up water?