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Updated: May 27, 2026

Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling
Published on: June 25, 2015
Controlled gene expression in bifidobacteria by use of a bile-responsive element
Lorena Ruiz1, Pablo Álvarez-Martín, Baltasar Mayo
1Department of Microbiology and Biochemistry of Dairy Products, Instituto de Productos Lácteos de Asturias (IPLA), Consejo Superior de Investigaciones Científicas (CSIC), Villaviciosa, Asturias, Spain.
Abstract:
The promoter activity of the upstream region of the bile-inducible gene betA from Bifidobacterium longum subsp. longum NCC2705 was characterized. DNA fragments were cloned into the reporter vector pMDYAbfB, and the arabinofuranosidase activity was determined under different in vitro conditions. A segment of 469 bp was found to be the smallest operational unit that retains bile inducibility. The reporter activity was strongly affected by the presence of ox gall, cholate, and conjugated cholate, but not by other bile salts and cell-surface-acting compounds. Remarkably, this bile-inducible system was also active in other bifidobacteria containing betA homologs.
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