I'm a bit concerned that they don't mention a particular strain of B. Subtilis.

There are hundreds of documented strains, and they don't all eat/produce the same things (at least not in the same ratios)

Some have been documented to reduce inflammation and restore tight-junction function in epithelial walls (where other strains did not).

Others have been shown to reverse the accumulation of α-synuclein. That has been implicated as a cause or symptom of Parkinson's disease.