Matemàtiques

The optimal residence time in the inducing reactor of a continuous two-stage system has been studied in order to maximize the yield in such a process. The attention has been focused on the case in which the product (or one of its forms) appears in the culture only transiently after the induction. Whereas in some cases the two-stage system is able to improve the yield and to allow a continuous product concentration in the outgoing stream, in others, and depending on how the product is accumulated in the induced culture, no optimal residence time can be found, and a higher productivity will be achieved by using the one-stage continuous strategy or a batch fermentation.

Abstract The ability to synthesize both recombinant and homologous cell proteins has been studied during the stationary phase of E. coli batch cultures. The anabolic potential of the culture dramatically decreases when entering into the stationary phase but slightly recovers several hours latter. In addition, CI857-controlled production of β-galactosidase is transiently enhanced at late stages of the stationary phase. These results show a non-synchronous distribution of the biosynthetic resources throughout culture growth phases, favouring the ...

Cell growth and production of recombinant proteins in stationary phase cultures of Escherichia coli recover concomitantly with spontaneous lysis of a fraction of the ageing cell population. Further exploration of this event has indicated that sonic cell disruption stimulates both cell growth and synthesis of plasmid-encoded recombinant proteins, even in exponentially growing cultures. These observations indicate an efficient cell utilisation of released intracellular material and also that this capability is not restricted to extreme ...

Bacterial inclusion bodies (IBs), mechanically stable, submicron protein particles of 50-500 nm dramatically favor mammalian cell spread when used for substrate surface decoration. The mechanisms supporting fast colonization of IB-modified surfaces have not yet been identified. This study provides evidence of mechanotransduction-mediated stimulation of mammalian cell proliferation on IB-decorated surfaces, as observed by the enhanced phosphorylation of the signal-regulated protein kinase and by the dramatic emission of filopodia in the presence of IBs. Interestingly, the results also show that IBs are highly bioadhesive materials, and that mammalian cell expansion on IBs is synergistically supported by both enhanced adhesion and mechanical stimulation of cell division. The extent in which these events influence cell growth depends on the particular cell line response but it is also determined by the genetic background of the IB-producing bacteria, thus opening exciting possibilities for the fine tailoring of protein nanoparticle features that are relevant in tissue engineering.