Microbially expressed thermotolerant phytase for animal feed

A method to prepare a thermotolerant phytase, comprising:

• expressing in a microbial host cell an expression cassette comprising a promoter operably linked to a nucleic acid molecule encoding a thermotolerant phytase which retains at least 40% activity after 30 minutes at 60° C. and has a specific activity of greater than 200 U/mg at pH 4.5 and 37° C. wherein the thermotolerant phytase comprises the polypeptide sequence depicted in SEQ ID NO.1 or a variant polypeptide thereof having a deletion or substitution of one or more amino acids from the N-terminal and/or C-terminal of said polypeptide sequence;
• and obtaining the expressed thermotolerant phytase by disrupting the microbial host cells.