Okay anyone planning on brewing a sour soon? If I were I'd jump on this real fast just to test out. Hell if I can find this stuff in a store I will give it a shot in a small starter to see if I can get it to sour rather quickly.
When looking at one of my brewing microbiology reference books I remembered a table of lactic acid bacteria. On the list it would specify what sugars it would ferment based on the types of sugars they used for species differentiation. At the end of the list was this species in the title. It ferments most all the sugars used for differentiation vs. L. brevis which ferments like 3 of them. So it made me do some research. Apparently this species may have hop resistance just like some specific strains of L. brevis. The hop resistance is greatly attributed to the horA gene which basically gives them a stronger cell wall to withstand the hop acids (paraphrasing).
Anyhow I found a cheap source of the culture potentially, well cheap compared to a culture company. The strain is specifically linked to digestive therapeutics. I, unfortunately, cannot find any research linking this specific strain (Lactobacillus plantarum 299v) to a horA gene in two quick searches today. Anyhow with that said a small 80mL bottle has quite a bit of bacteria and it may provide quite the culture to start a sour beer. Most of the shots are flavored but it also comes in a small plain variety which may be just fine for direct pitches.
For the lazy ones not willing to look through the site. Only objectionable thing in there is a tiny bit of stevia it seems. However at 80mL to even a 5gal batch it's only 0.4% of the volume. So I think the 20bil cfus in the bottle would be worth the little bit of stevia.