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.
Marounek
M
M
Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, 142 20, Prague, Czech Republic. marounek@iapg.cas.cz
Brenová
N
N
Suchorská
O
O
Mrázek
J
J
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