Recombinant DNA (I) coding for a phytase polypeptide has a sequence coding for the mature wild-type Escherichia coli phytase with at least one of the following variations (i) a K74D mutation, (ii) a combination of N139R and D142E mutations, (iii) a combination of L145I and L198I mutations, (iv) a V200P mutation and (v) N- and/or C-terminal attachment of an Aspergillus niger acid phosphatase or phytase sequence fragment, where variations (iii) and (iv) can only be present in combination with variation (i), (ii) and/or (v). Independent claims are also included for: (1) phytase polypeptide (II) encoded by (I)； (2) DNA construct comprising an optional promoter, optional signal and marker sequences, (I), a terminator and optional 5' and 3' flanking sequences； (3) vector comprising a construct as above； (4) transformed fungal, yeast, bacterial or mammalian cell containing (I)； (5) producing (II) by culturing a transformed cell as above； (6) composition comprising (II).
