<unk>  is a genus of gram-positive, nonmotile, often branched anaerobic bacteria. They are ubiquitous inhabitants of the gastrointestinal tract though strains have been isolated from the vagina and mouth (B. dentium) of mammals, including humans. Bifidobacteria are one of the major genera of bacteria that make up the gastrointestinal tract microbiota in mammals. Some bifidobacteria are used as probiotics. Before the 1960s,<unk>  species were collectively referred to as "Lactobacillus bifidus".
Bifidobacterium
Lactobacillus acidophilus
Faecalibacterium
Lactobacillus
Campylobacter upsaliensis
Salmonella
Clostridioides difficile 
Prevotella bivia