This species originally appeared to be one of the good lactobacillus. I though after yesterday’s post, it would be good to drill down into it to be sure. Swanson sells it as a single species probiotic. Most of the studies are for specific strains (which are not currently on the market).
At a high level, it looks very good
” L. plantarum attracted many researchers because of its wide applications in the medical field with antioxidant, anticancer, anti-inflammatory, antiproliferative, anti-obesity and antidiabetic properties.”  [Full Text]
and drilling down into some details, it continue to look good
- Lactobacillus plantarum CCFM639 alleviates aluminium toxicity .
- Anti-obesity effect of milk fermented by Lactobacillus plantarum NCDC 625 alone and in combination with herbs on high fat diet fed C57BL/6J mice .
- Lactobacillus plantarum NCU116 attenuates cyclophosphamide-induced intestinal mucosal injury, metabolism and intestinal microbiota disorders in mice .
- Distinct effects of Lactobacillus plantarum KL30B and Escherichia coli 3A1 on the induction and development of acute and chronic inflammation .
- In vitro probiotic characteristics of Lactobacillus plantarum ZDY 2013 and its modulatory effect on gut microbiota of mice .
- “Lactobacillus plantarum ZDY 2013 was sensitive to some antibiotics (e.g., macrolide, sulfonamides, aminoglycoside, tetracyclines and β-lactams), whereas it was resistant to glycopeptides, quinolones, and cephalosporins antibiotics.” 
- Plantaricin IIA-1A5 from Lactobacillus plantarum IIA-1A5 displays bactericidal activity against Staphylococcus aureus .
- ” A cocktail containing L. plantarum + B. longum Bb46 + B. longum LMG 13197 best inhibited S. aureus” 
- Lactobacillus plantarum K-1 decreases histamines    increases 
BUT then I hit this set of studies for IBS
- Clinical trial: Lactobacillus plantarum 299v (DSM 9843) improves symptoms of irritable bowel syndrome   Not repeated in   unfavorable in 
HOWEVER, if you are low in Iron, then this is a definite to take.. see this post.
If you have IBS, definitely avoid this one. While it has some good benefits for things like aluminum – it seems not to be a good choice for CFS/IBS. IBS studies are a good proxy for CFS (when no studies exist), and multiple studies show no effect (for the same strain that occasionally have positive effect), or negative effect.
Ken’s Rule: If a probiotic has been tested for IBS with good results (and no bad ones) then it is recommended. Good results with other digestive issues — but no IBS, also recommended. No results or negative, places it in the suspect camp.
My favorites are:
- Prescript Assist