Bifidobacterium apri sp nov., a thermophilic actinobacterium isolated from the digestive tract of wild pigs (Sus scrofa)

Fresh samples of intestinal contents of three wild pigs originating from the Central Bohemia region were examined for the presence of bifidobacterial strains. During the study, we isolated many fructose-6-phosphate phosphoketolase-positive, strictly anaerobic, irregular rod-shaped bacterial isolates. Three of them were preliminarily identified as representing a novel species of the genus Bifidobacterium because their 16S rRNA gene sequence similarity with the closest relatives of thermophilic bifidobacteria (Bifidobacterium boum DSM 20432(T), Bifidobacterium thermophilum DSM 20210(T), Bifidobacterium thermacidophilum subsp. porcinum LMG 21689(T), Bifidobacterium thermacidophilum subsp. thermacidophilum DSM 15837(T)) was in the range of 97.9 - 98.4 %. All three bacterial isolates had identical 16S rRNA, dnaJ1, fusA, gyrB and rplB gene sequences. Isolate RP115(T) was chosen as a representative of the bacterial group and DNA G+C content (mol%) determination, biochemical tests and analyses of physiological and morphological characteristics, habitat and chemotaxonomic traits (peptidoglycan structure, cellular fatty acids and polar lipids profile) were performed. The DNA-DNA hybridization analyses of RP115(T) and species representing the group of thermophilic bifidobacteria revealed values in the range from 33 to 53 %. This fact, together with relatively low sequence similarities of particular phylogenetic markers among examined bacterial strains and the phenotyping and chemotaxonomy results obtained, indicated that the evaluated bacterial isolate should be classified as representing a separate taxon within the specific group of thermophilic bifidobacteria. The name Bifidobacterium apri (of boar) sp. nov. has been proposed for the representative strain RP115(T) (=CCM 8605(T)=DSM 100238(T)=LMG 28779(T)).