The probiotics were searched from the Pubchem database (the all fields search option), and additionally from Google and Baidu, by using the keyword "probiotics" and “probiotic” respectively.

The marketed probiotics were selected based on the following criteria:

The marketed probiotics for use in humans are those described as approved by a national authority (1), commonly used by humans for treatment purposes (2), or as a key probiotic species in a commercial product, brand name, dietary supplement or food (3).
The marketed probiotics for use in animals are those reported to be commonly used or as part of a commercial product for the growth, protection and health maintenance of animals in veterinary medicine or agriculture.
The marketed probiotics used for plants are those described to be commonly used or as part of a commercial product for the nutrient supply, growth, product yield, and defense of plants in agricultures.

The clinical trial probiotics are those explicitly mentioned to have undergone "randomized" or "controlled" trials(4). The field trial probiotics for use in animals or plants are those described as having entered a field trial or field evaluation(5).

The research probiotics are those reportedly having beneficiary function in in-vitro, in-vivo or other laboratory studies, but not yet being marketed or tested in a clinical trial.

1. Amagase H. Current marketplace for probiotics: a Japanese perspective. Clin Infect Dis. 2008 Feb 1;46 Suppl 2:S73-5.
2. Hungin AP, et al. Systematic review: probiotics in the management of lower gastrointestinal symptoms in clinical practice -- an evidence-based international guide. Aliment Pharmacol Ther. 2013 Oct;38(8):864-86.
3. Saxelin M. Probiotic formulations and applications, the current probiotics market, and changes in the marketplace: a European perspective. Clin Infect Dis. 2008 Feb 1;46 Suppl 2:S76-9.
4. Trois, L., Cardoso, E.M. and Miura, E. Use of probiotics in HIV-infected children: a randomized double-blind controlled study. Journal of tropical pediatrics. 2008. 54:19-24.
5. Alexopoulos, C., Georgoulakis, I.E., Tzivara, A., Kyriakis, C.S., Govaris, A. and Kyriakis, S.C. Field evaluation of the effect of a probiotic-containing Bacillus licheniformis and Bacillus subtilis spores on the health status, performance, and carcass quality of grower and finisher pigs. Journal of veterinary medicine. A, Physiology, pathology, clinical medicine. 2004. 51:306-312.