1,720,988 research outputs found

    Mechanical stability and diffusional resistance of a polymeric gel used for biocatalyst immobilization

    No full text
    The mechanical strength of gelatin gels insolubilized by crosslinking with formaldehyde was measured at various gelatin percentages and formaldehyde-to-gelatin ratios. This property was shown to be related to the characteristic sponge-like structure of the insolubilized gelatin gel, a structure that unexpectedly is also responsible for the resistance to substrate and product diffusion. A comparison between immobilizates of invertase and invertase-active yeast cells prepared with different gelatin concentrations showed that the enzyme, in contrast to cells, is deeply involved in the gel insolubilization process. The catalytic behavior of agar, κ-carrageenan, alginate, and gelatin immobilizates was compared under the same conditions of cell loading. The mechanical strength of gelatin gels insolubilized by crosslinking with formaldehyde was measured at various gelatin percentages and formaldehyde-to-gelatin ratios. This property was shown to be related to the characteristic sponge-like structure of the insolubilized gelatin gel, a structure that unexpectedly is also responsible for the resistance to substrate and product diffusion. A comparison between immobilizates of invertase and invertase-active yeast cells prepared with different gelatin concentrations showed that the enzyme, in contrast to cells, is deeply involved in the gel insolubilization process. The catalytic behavior of agar, k-carrageenan, alginate, and gelatin immobilizations was compared under the same conditions of cell loading

    Mathematical modeling as a tool to describe and optimize heterologous protein production by yeast cells in aerated fed-batch reactor

    No full text
    In this work, two recombinant yeast strains, the prototrophic non-conventional Zygosaccharomyces bailii [pZ3KlIL-1beta] and the auxotrophic Saccharomyces cerevisiae BY4741[PIR4-IL1beta], both producing human interleukin-1beta, have been cultured in aerated fed-batch using glucose as limiting substrate. A mathematical model of the fed-batch reactor has been developed, based on mass balance equations of the main process variables: biomass, glucose and product, and implemented with kinetic expressions to explain the yeast behaviour within the aerated fed-batch reactor. In the case of Z. bailii, the mathematical model evidenced the suitability of the fermentative inoculum with respect to the respiratory one at the start of the exponential feeding. In the case of the auxotrophic S. cerevisiae BY4741, the modellistic approach has permitted to highlight a strong deviation from the expected behaviour and quantify the glucose amount that is spent for maintenance rather than for growth, thus impairing the outcome of the bioprocess
    corecore