Veillonella are Gram-negative anaerobic cocci. This bacterium is well known for its lactate fermenting abilities. They are a normal bacterium in the intestines and oral mucosa of mammals. In humans they have been rarely implicated in cases of osteomyelitis and endocarditis, for example with the species Veillonella parvula.
Fermentation of lactate to propionate and acetate is by the methylmalonyl-CoA pathway. Little ATP is produced in this fermentation. High substrate affinity is suggested to be the reason.
Lactate → acetate + 2 propionate + CO2 + H2O
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)  and National Center for Biotechnology Information (NCBI) and the phylogeny is based on 16S rRNA-based LTP release 111 by The All-Species Living Tree Project 
- van den Bogert,, Bartholomeus; Erkus, Oylum; Boekhorst, Jos; de Goffau, Marcus; Smid, Eddy J; Zoetendal, Erwin G; Kleerebezem, Michiel; Kleerebezem,, Michiel (2013). "Diversity of human small intestinal Streptococcus and Veillonella populations". FEMS Microbiology Ecology 85 (2): 376–388. doi:10.1111/1574-6941.12127. PMID 23614882.