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Abstract

A mathematical model of a hybrid culture system supported with a stationary layer of liquid perfluorochemical (PFC) as a source of O2 for cells which grow in the aqueous phase of culture medium has been developed and discussed. The two-substrate Monod kinetics without inhibition effects, i.e. the Tsao-Hanson equation, has been assumed to characterise the biomass growth. The Damköhler number which relates the growth rate to the mass transfer effects has been used to appraise the regime (i.e. diffusion-limited or kinetics) of the whole process. The proposed model predicted accurately previously published data on the submerged batch cultures of Nicotiana tabacum BY-2 heterotrophic cells performed in a culture system supported with a stationary layer of hydrophobic perfluorodecalin as a liquid O2 carrier. Estimated values of the parameters of the model showed that the process proceeded in the kinetics regime and the growth kinetics, not the effects of the mass transfer between aqueous phase and liquid PFC, had essential influence on the growth of biomass.
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Abstract

Efforts were made to demonstrate that in biorefineries it is possible to manufacture all the commodities required for maintaining human civilisation on the current level. Biorefineries are based on processing biomass resulting from photosynthesis. From sugars, oils and proteins, a variety of food, feed, nutrients, pharmaceuticals, polymers, chemicals and fuels can further be produced. Production in biorefineries must be based on a few rules to fulfil sustainable development: all raw materials are derived from biomass, all products are biodegradable and production methods are in accordance with the principles of Green Chemistry and Clean Technology. The paper presents a summary of state-of-the-art concerning biorefineries, production methods and product range of leading companies in the world that are already implemented. Potential risks caused by the development of biorefineries, such as: insecurities of food and feed production, uncontrolled changes in global production profiles, monocultures, eutrophication, etc., were also highlighted in this paper. It was stressed that the sustainable development is not only an alternative point of view but is our condition to survive.
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Abstract

Kinetic resolution of (R)- and (S)-mandelic acid by its transesterification with vinyl acetate catalysed by Burholderia cepacia lipase has been studied. The influence of the initial substrate concentration on the kinetics of process has been investigated. A modified ping-pong bi-bi model of enzymatic transesterification of (S)-mandelic acid including substrate inhibition has been developed. The values of kinetic parameters of the model have been estimated. We have shown that the inhibition effect revealed over a certain threshold limit value of the initial concentration of substrate.
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Abstract

One of the actual challenges in tissue engineering applications is to efficiently produce as high of number of cells as it is only possible, in the shortest time. In static cultures, the production of animal cell biomass in integrated forms (i.e. aggregates, inoculated scaffolds) is limited due to inefficient diffusion of culture medium components observed in such non-mixed culture systems, especially in the case of cell-inoculated fiber-based dense 3D scaffolds, inside which the intensification of mass transfer is particularly important. The applicability of a prototyped, small-scale, continuously wave-induced agitated system for intensification of anchorage-dependent CP5 chondrocytes proliferation outside and inside three-dimensional poly(lactic acid) (PLA) scaffolds has been discussed. Fibrous PLA-based constructs have been inoculated with CP5 cells and then maintained in two independent incubation systems: (i) non-agitated conditions and (ii) culture with wave-induced agitation. Significantly higher values of the volumetric glucose consumption rate have been noted for the system with the wave-induced agitation. The advantage of the presented wave-induced agitation culture system has been confirmed by lower activity of lactate dehydrogenase (LDH) released from the cells in the samples of culture medium harvested from the agitated cultures, in contrast to rather high values of LDH activity measured for static conditions. Results of the proceeded experiments and their analysis clearly exhibited the feasibility of the culture system supported with continuously wave-induced agitation for robust proliferation of the CP5 chondrocytes on PLA-based structures. Aside from the practicability of the prototyped system, we believe that it could also be applied as a standard method offering advantages for all types of the daily routine laboratory-scale animal cell cultures utilizing various fiber-based biomaterials, with the use of only regular laboratory devices.
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