Figure 1.
Fluorescence microscopy and flow cytometry analyses of yeast cells.
Figure 2.
Phytase activity after induction with methanol and after treatment with laminarinase.
A: Time dependence of the activity of cell surface phytase after induction with methanol. B: Cell surface phytase activity after laminarinase treatment. Column 1 represents cell wall fractions without treatment with laminarinase. Columns 2 and 4 represent cell wall fractions after laminarinase treatment, and column 3 and 5 represent supernatant fractions after laminarinase treatment. Columns 2 and 3 show phytase activities after treatment with 5 mU of laminarinase, while columns 4 and 5 represent the remaining activities after treatment with 50 mU of laminarinase. All activities were compared to the activity of the whole cell surface phytase, with GS115/ZαA as a background measurement.
Figure 3.
Effect of temperature and pH on the activity of the cell surface and secreted phytases.
A: Activity of cell surface and secreted phytases at different temperatures. B: Thermostability of cell surface phytase. C: Thermostability of secreted phytase. D: Activity of cell surface phytase, secreted phytase and the supernatant fractions of cell surface phytase treated with 50 mU of laminarinase at different pH values. E: The pH stability of cell surface phytase, secreted phytase and the supernatant fractions of cell surface phytase treated with 50 mU of laminarinase.
Table 1.
Effect of metal ions on cell surface and secreted phytases.
Figure 4.
In vitro digestibility test of cell surface and secreted phytases.
A: Measured phosphate (Pi) released from a corn-based diet mixed with cell surface or secreted phytases. B: Simulation of the pelleting process (i.e., incubation for 3 min at 80°C or 5 min at 90°C prior to activity measurement), followed by determination of the amount of released Pi. The levels of released Pi were compared with samples without heat treatment. GS115/ZαA served as a background measurement.