Genetic Instability of Probiotic Characteristics in the Bifidobacterium longum subsp. longum B379M Strain during Cultivation and Maintenance

摘要

The stability of inheritance of several genes in the Russian commercial strain Bifidobacterium lon- gum subsp. longum B379M during cultivation and maintenance under laboratory conditions has been studied. The examined genes code for probiotic characteristics, such as utilization of several sugars (lacA2 gene, encoding β-galactosidase; ara gene, encoding arabinosidase; and galA gene, encoding arabinogalactan endo-β-galactosidase); synthesis of bacteriocins (lans gene, encoding lanthionine synthetase); and mobile gene tet(W) of resistance to the antibiotic tetracycline. The other gene families studied include the genes respon- sible for signal transduction and adaptation to stress conditions in the majority of bacteria (serine/threonine protein kinases and the toxin-antitoxin systems of MazEF and RelBE families) and transcription regulators (genes encoding WhiB family proteins). Genomic DNA was analyzed by PCR using specially selected prim- ers. A loss of the genes galA and tet(W) has been shown. It is proposed to expand the requirements on probi- otic strains, namely, to control retention of the key probiotic genes using molecular biological methods.