Abstract: In Chinese hamster ovary cells for producing proteins, the growth phase is uncoupled from the production phase. In a method for preparing the Chinese hamster ovary cells and with the use of the Chinese hamster ovary cells for preparing proteins, a seed culture of high cell density is prepared which cells are grown to confluence and genetic material is transferred into the cells after the formation of a confluent surface (G1 phase).

Abstract: Stem cells or other organ-function cells are cultivated in a fluidized bed system on macroporous glass carrier bodies treated with a structure protein such as gelatin and an extracellular matrix protein such as fibronectin, and coated with a stroma cell layer. Glass carriers coated with gelatin are added to a fluidized bed reactor, and a culture medium containing an extracellular matrix protein is added to bind the protein to the gelatin. Stromal cells are then added and the cells are cultured to immobilize the cells on the carriers containing the bound protein. Immature organ-function cells are added to the reactor, and while generating a fluidized bed of the carriers in the culture medium, the culture medium is recirculated from and to the reactor in a recirculation loop. Bubble-free aeration of the culture medium is effected to cultivate the immature organ-function cells on the carriers to obtain both mature differentiated organ-function cells and progenitor organ-function cells.

Abstract: A cell culture reactor can have one or more gasification modules in which tubular membrane hoses surround rigid inner tubes which extend above the membranes to communicate with gas inlets or outlets. The tube is anchored in a closure member at the lower end of the membrane.

Abstract: A process for the removal of ammonium from aqueous liquids, especially from fermentation broths, is disclosed. The process uses a cation exchanger membrane which separates a liquid on a donor side that is to be depleted of NH.sub.4.sup.+ from a solution on an acceptor side whose pH is higher than on the donor side. Because of the equilibriumNH.sub.4.sup.+ .revreaction.NH.sub.3 +H+there is on the acceptor side increased formation of NH.sub.3. This is continuously removed, in particular by reducing the pressure and/or passing through inert gas, or by selective transport through another microporous membrane into an acid protonation solution, so that a NH.sub.4.sup.+ concentration gradient is maintained across the membrane. A similar content, apart from the ammonium concentration, of concomitant cations on the donor and acceptor side and/or a high ratio of the solution volumes on the donor side and the acceptor side ensures that the solution on the donor side to be depleted of NH.sub.4.sup.