摘要：We have cloned and characterised fragments of Bifidobacterium breve chromosomal DNA which appear to be specific to the species B. breve that is commonly found in the human intestine and in dairy products. Twenty-five Hind-III-digested DNA fragment as probes were screened for hybridisation with pure cultures of five species of bifidobacteria (B. adolescentis, B. bifidum, B. breve, B. infantis, B. longum). Two of the fragments hybridised only to the species B. breve. These cloned fragments were analysed for specificity with another 31 strains of 15 species of bifidobacteria. One of the cloned fragments (BB22 1.8 kilobases) was shown to specifically hybridise with B. breve. Moreover, 49 colonic isolates likely to be encountered in human faeces (containing 47 species or 18 genera) were tested with the BB22 probe. None of the intestinal bacteria tested showed any hybridisation except B. breve. The intraspecies hybridisation homology was quite low, so it is possible to make a clear distinction between the species B. breve and any of the non-B. breve colonic bacterial species in the autoradiogram. These data demonstrate that this DNA fragment is a species-specific DNA probe for the rapid and reliable identification of B. breve.Keywords: Bifidobacterium breve; Probe; Identification: Homology.
