Truncated phytases of bifidobacteria and uses thereof

[EN] The invention relates to an isolated polynucleotide consisting of a nucleotide sequence coding for an amino acid sequence of Bifidobacterimn having at least 55% identity with amino acid sequence SEQ ID NO: 1, in which said amino acid sequence lacks a sequence coding for the transmembrane helix, located at the carboxy-tenninal end of the original sequence, and in which said amino acid sequence is a protein of which the main activity is phytase. Preferably, the polynucleotide originates from strains of Bifidobacterium pseudocatenulatum (B. pseudocatenulatum) ATCC279l9 or Bifidobacterium longum subsp. infantis (B. longmn subsp. infantis) ATCC15697. The invention also relates to the use of the polynucleotide, or to any of the products described in the invention, in arder to reduce the phytate content of a food or to produce myo-inositol triphosphate (InsP3).