Wow, what a research project. I found a couple review papers on probiotics (PDF1, PDF2) that summarized the functions of the Lactobacillus and one of the Bifidobacterium strains you listed. A lot of the research in the first study is based on animal studies, but the second one bases its conclusions solely on human studies. Probiotic.org also has a lot of info, but their referencing is a little sketchy, so I only referenced them here if I had to.
Bifidobacterium (previously known as L. bifidus)
- B. bacterium breve: Keeps yeast in check (prevents yeast infections), shortage has been linked to antibiotic-associated diarrhea, allergies, and irritable bowel syndrome symptoms (probiotics.org)
- B. bacterium longum: May help prevent gastrointestinal side effects cased by antibiotic treatment (PDF2)
Lactobacillus: Improves digestion, reduces symptoms of lactose intolerance, improves immunity via improved mucous secretion (PDF1)
- L. acidophilus: Keeps yeast in check, helps prevent colon cancer, helps prevent urogenital infections (like bladder infections), lowers blood cholesterol (PDF1), reduces symptoms of lactose intolerance, may help reduce chronic heart burn (PDF2)
- L. bulgaricus: May help prevent antibiotic-related diarrhea (PDF2)
- L. casei: May play a role in bladder and colon cancer treatment/prevention (PDF2)
- L. plantarum: Produces and preserves nutrients, vitamins, and antioxidants, eliminates toxic components from food, positive effect on immunity in some cases (PDF1), reduces many symptoms of irritable bowel syndrome (PDF1 & PDF2), may help reduce chronic heart burn (PDF2)
- L. rhamnosus (includes L. GG): helps prevent colon cancer, keeps yeast in check, helps prevent urogenital infections, reduces food allergies and atopic dermatitis, boosts immunity (PDF1), decreases duration and/or prevents a number of different types of diarrhea (PDF1, PDF2)
Streptococcus: According to this abstract, they're not yet well-studied.
- S. diacetylactis: This is a probiotic, but I couldn't find out much more about it.
- S. thermophilus: Not a probiotic, since it's destroyed during digestion (Wikipedia)
- Saccharmyces florentinus: I couldn't find much on this specifically, but other types of Saccarmyces (which are yeasts) are apparently associated with various health benefits (probiotics.org).
- Lactococcus lactis: Immune stimulation, improves digestive health, reduces antibiotic-associated diarrhoea (Wikipedia)
- Leuconostoc cremoris: From this study it sounds like, when combined with other probiotics, leuconostroc cremoris decreases the amount of lactose in milk, making it easier to digest for people with lactose intolerance.
If you're interested in digestion/absorption, you may also want to look into prebiotics.