ABSTRACT
Currently, over 30 species are included in the genus Biƒdobacterium. They form a close phylogenetic group and show high similarity (>93%) in the 16S rRNA sequences.4 The Biƒdobacterium genus is included in the phylum Actinobacteria, class Actinobacteria, subclass Actinobacteridae, order Biƒdobacteriales, and family Biƒdo bacteriaceae. Phylogenetic studies, based on sequence comparison of 16S rRNA sequences and housekeeping genes, have clustered some Biƒdobacterium species in six phylogenetic clusters named Biƒdobacterium boum, Biƒdobacterium
asteroides, Biƒdobacterium adolescentis, Biƒdobacterium longum, Biƒdobacterium pullorum, and Biƒdobacterium pseudolongum.5 Other species have displayed a large phylogenetic distance and have not been assigned to any speciŠc cluster (Figure 5.1). The species included in the genus Biƒdobacterium are B. adolescentis, B. angulatum, B. animalis, B. asteroides, B. biƒdum, B. bombi, B. boum, B. breve, B. catenulatum, B. choerinum, B. coryneforme, B. cuniculi, B. dentium, B. gallicum, B. gallinarum, B. indicum, B. longum, B. magnum, B. merycicum, B. minimum, B. mongoliense, B. pseudocatenulatum, B. pseudolongum, B. psychraerophilum, B. pullorum, B. ruminantium, B. saeculare, B. scardovii, B. subtile, B. thermacidophilum, B. thermophilum, and B. tsurumiense.6-9 Further more, B. animalis comprises of two subspecies (animalis and lactis), as well as B. pseudolongum (subsp. globosum and pseudolongum), and B. thermacidophilum (subsp. thermoacidophilum and porcinum), whereas the species B. longum is subdivided in the subspecies longum, infantis, and suis (Figure 5.1).
