Fig. 1

Cladograms of bifidobacteria strains harbored by A) human hosts and B) multiple hosts and environments. 1A|Phylogenetic relationship of human-derived Bifidobacterium strains based on 107 marker genes (n = 60 + outgroup). The prominent species, B. longum (31.7%), B. breve (23.3%), and B. animalis (10%), are shaded in different colors. 1B|Phylogenetic relationship of Bifidobacterium strains harbored by multiple hosts based on 107 marker genes (n = 129 + outgroup). The prominent species, B. pseudolongum (12.4%), B. longum (10.9%) and B. animalis (10.1%), are shaded in different colors. For both cladograms, the outermost ring represents the different isolation sources. Bootstrap values higher than 70% are represented with blue circles. Strains from the Alloscardovia genus were used as outgroups for both phylogenetic trees (accession numbers JWAI01000000 and NEKB01000000). Note that the “child” category refers to ages 2 through 6 years old while “infant” is younger. The “mammal” category indicates a mammal with only 1 sample size, including giraffe (n = 1), hippopotamus (n = 1), llama (n = 1), and wallaby (n = 1). Also, the “primate” category indicates non-human primates, and “probiotic” had an original, unknown isolation source that may overlap with the other categories