The present invention relates to enzymes and processes. In particular, there is described a host cell transformed or transfected with a nucleic acid encoding a bacterial phytase enzyme and variants thereof.
1. A non-naturally occurring phytase comprising a polypeptide having at least 95% sequence identity with the amino acid sequence of the polypeptide encoded by SEQ ID NO:2 and comprising a substitution at position Q289, corresponding to the position numbering of SEQ ID NO: 3, wherein the polypeptide has specific phytase activity of at least 300 U/mg determined by incubating said polypeptide in a solution containing 2 mM phytate, 0.8 mM CaCl 2 in 200 mM sodium acetate buffer at pH 3.5, at a temperature of 37° C.
2. The non-naturally occurring phytase according to claim 1 , having the amino acid sequence of SEQ ID NO: 3 and a substitution at position Q289.
3. The non-naturally occurring phytase according to claim 1 , wherein said polypeptide is isolated and/or purified.
4. The non-naturally occurring phytase polypeptide according to claim 1 , having an activity maximum at about pH 4.5, wherein the activity is determined by incubating the phytase in a solution containing 2 mM phytate, 0.8 mM CaCl 2 in 200 mM sodium acetate buffer at a temperature of 37° C.
5. The non-naturally occurring phytase according to claim 1 , having an activity maximum at around pH 3 to 6, wherein the activity is determined by incubating said phytase in a solution containing 2 mM phytate, 0.8 mM CaCl 2 in 200 mM sodium acetate buffer at a temperature of 37° C.
6. The non-naturally occurring phytase according to claim 1 , that comprises at least one substitution in at least one of the following positions (numbering according to the numbering in SEQ ID NO: 3): K59, T70, A122, D125, T167, H193, F197, T204, T209, A211, S221, I223, S225, K240, A242, D244, A268, S281, A294, N303, I336 or N351.
7. The non-naturally occurring phytase according to claim 6 , having a Q289Y substitution and a substitution: K59E; T167V; K240T; T1671; K240E; D244C; T209K or F197S.
8. The non-naturally occurring phytase according to claim 6 , having substitutions in the following positions:
A122T/T167I/F197S/T209K/A211P/K240E/A242S/S281L/Q289Y/A294E/N303K; or
D125E/T167I/H193R/F197S/T204I/T209K/A211P/K240E/A268V/Q289H/A294E/N303K;
or
A122T/T167I/H193R/F197S/T204I/T209K/A211P/K240E/A268V/Q289H/A294E/N303K/I 336F or;
N70Y/D125E/T1671/H193R/F197S/T204I/T209K/A211P/K240E/A268V/Q289H/A294E/N303K.
9. The non-naturally occurring phytase according to claim 1 , having an activity maximum at about pH 4 to 5, wherein said activity is determined by incubating the phytase in a solution containing 2 mM phytate, 0.8 mM CaCl 2 in 200 mM sodium acetate buffer at a temperature of 37° C.
10. The non-naturally occurring phytase according to claim 6 , having substitutions in the following positions:
A122T/F1671/F197S/F209K/A211P/K240E/A242S/S281L/Q289Y/A294E/N303K.
11. The non-naturally occurring phytase according to claim 1 wherein the phytase has higher thermal stability and/or higher specific activity and/or higher proteolytic stability compared to the phytase enzyme encoded by SEQ ID NO: 2, without the substitution(s).
12. The non-naturally occurring phytase according to claim 1 , wherein the substitution at position Q289 is Q289Y.
13. A food or animal feed composition comprising the non-naturally occurring phytase according to any one of claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 or 12 .
14. The food or animal feed composition according to claim 13 , produced by spraying the non-naturally occurring phytase in liquid form onto food or animal feed.
15. The food or animal feed composition according to claim 13 , produced by mixing the non-naturally occurring phytase as a dry product with food or animal feed.