Sounds a tad pointless?
There are any number of widely available and cheap organic acids available industrially so why not simply use one of these. Alternatively, as they showed that Sulphuric (yes that's the "correct" spelling in this old British head!) was superior (and presumably any other readily available mineral acid would be too) - sooo what's the story here? They used spent growth medium, so presumably again this isn't a bacterium that can be grown on on the phospho-gypsum so nowt special about it.
Is there an industry with an abundance of this stuff as a waste by-product or something?
Biting the hand that feeds IT
