Phytase activity in rabbit cecal bacteria.
The presence of phytase activity was demonstrated in 26 strains of rabbit cecal bacteria. In 25 strains a low phytase activity, 0.10-0.62 micromol phosphate released per min per mg protein, was found. High activity (2.61 micromol/min per mg protein) was found in the strain PP2 identified as Enterococcus hirae. Phytase activity was cell-associated, being higher in the cell extract than in the cell walls. Extracellular phytase activity and cell-associated phosphatase activity were not detected. Phytase activity was optimal around pH 5.0, which is below the physiological cecal pH range. The K (m) determined using the Lineweaver-Burk plot was 0.19 micromol/mL. Cations Fe(3+), Cu(2+) and Zn(2+) at 0.5 mmol/L decreased phytase activity in sonicated cells of E. hirae by 99.4, 90.7 and 96.5 %, respectively. In contrast, Mg(2+) increased activity by 11.0 %. Characteristics of E. hirae phytase (pH optimum, K (m), cation sensitivity) were similar to those of other bacterial phytases reported in the literature. Other bacteria with a high phytase activity may be present in the rabbit cecum but remain to be identified.
Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, 142 20, Prague, Czech Republic. marounek@iapg.cas.cz
M
M
Marounek
N
N
Brenová
O
O
Suchorská
J
J
Mrázek
D010832:6-Phytase / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001419:Bacteria / Q000737:chemistry / Q000201:enzymology / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002432:Cecum / Q000382:microbiology*; D016983:Enterococcus / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D004795:Enzyme Stability; D007700:Kinetics; D011817:Rabbits
D001426:Bacterial Proteins; D010832:6-Phytase