Studies On The Immobilized Cultivation Of Dictyostelium Discoideum With Polyurethane Foam

The cellular slime mould Dictyostelium discoideum (D.discoideum) belongs to Acrasiomzcetes. It shows promising characteristics as an expression system for the production of recombinant glycoprotein owing to perform a whole spectrum of post-translational modifications. These modifications are not completely identical to those of mammalian cells, but quite similar. However, the application of this system is seriously affected by slow growth rate as well as low maximal cell densitiy.The immobilization of D. discoideum with PUF was proposed in the present work. The effects of PUF's properties on the immobilization were examined. The results showed that PUF was a suitable carrier for the efficient immobilization of D. discoideum. Electron micrograph images indicated that how D. discoideum was immobilized on PUF carriers.And the effects of PUF addition and culture conditions were optimized to attain high density of D. discoideum, including PUF density, PUF particle size and PUF amount. Under the optimized culture condition, the highest cell density of D. discoideum in the pore volume of PUF (4.56×10⁷ ml^-1) was achieved in the shake flasks, which was 2-4 times higher than that of free-cell culture in the axenic medium. The activity of D. discoideum was not seriously affected by PUF immobilization. Doubling time of the immobilized D. discoideum was almost the same as that of free-cell culture.The 6-his tagged recombinant hFasL protein was successfully expressed in the D. dicoideum system. Using one-step Ni-affinity chromatography, the 6-his tagged hFasL protein was purified with a recovery rate of 92.1% and purity of 91.0%.