Cell Immobilization: Engineering Aspects

Abstract

The performance of immobilized cells is influenced by mass transport of substrates to the cells and of products from the cells to the bulk fluid, as well as the cell growth in the immobilization matrix. Both internal and external mass transfer limitations have to be considered in the design of immobilized cell systems. In this article, the various methods of measurement of the diffusion coefficient are reviewed. The influence of the presence and growth of living cells in the immobilization matrix on the diffusion coefficient is discussed. Internal diffusion in gel systems, microcapsules, and dense cell masses, that is biofilms, bioflocs, and mammalian cell aggregates is treated in detail, as well as internal mass transport by convection is considered. Finally, the mathematical modeling of reaction–diffusion systems of immobilized cells is discussed, with special attention to gel entrapment and microencapsulation.

Molecular Mechanism of Flocculation Self-Recognition in Yeast and Its Role in Mating and Survival

“…Due to diffusive mass transport limitations in a floc ( 120 ), nitrogen and carbon sources as well as oxygen drop to limiting concentrations inside the floc. This was confirmed by the transcriptome analysis: upregulation of genes involved with GO “gluconeogenesis” and “pentose-phosphate shunt” and genes involved in GO “response to starvation” and “autophagy” (see Table S2 in the supplemental material).…”

Influence of operational parameters on the fluid-side mass transfer resistance observed in a packed bed bioreactor

“…The results in Figure 2 indicates that coating has a significant effect on lag phase duration, as it was observed with chitosan coated beads being 30–40 min higher than non-coated beads. The reason is due to the reduction of external mass transfer as a result of increase in flow rate as glucose is easily transported to and from the beads surface by diffusion (Willaert and Flickinger 2009 ; Galaction et al 2012 ; Karagoz and Ozkan 2014 ).…”

“…These factors are severely affected by both external mass transfer limitations (transfer of reactants to and products from immobilized cell system) and internal mass transfer limitations (rate of transport inside the system (Saini and Vieth 1975 ; Converti et al 1985 ; Anselme and Tedder 1987 ; Galaction et al 2011 ). Cell immobilization technology, the localization of intact cells to a defined region of space with the preservation of catalytic activity presents for the biochemical process industry a radical advance, similar to the introduction of heterogeneous catalysis in the petrochemical and heavy chemical industries (Yu et al 2007 ; Willaert and Flickinger 2009 ; Duarte et al 2013 ). This justifies the interest in the research and development advanced materials for biotechnology with the combined effort of scientists from various fields to obtain polymers with well-defined structures and specific chemical, physicochemical, mechanical and biological properties which are used in cell enzyme entrapments (Terada et al 2006 ; Duarte et al 2013 ).…”

Valorization of Agro-Industrial By-products: Use of Rice Husk as a Source of Microorganisms to Denitrification of Water

“…At 25 °C and 30 °C, MOIM (48 h) and MOSO (24 h) provided equivalent denitrification rates. However, in 24 h, MOSO provided larger denitrification rates (double) than MOIM, because MOIM activity is limited and reduced when compared to free cells in suspension MOSO ( Figure 2) (Bankston et al, 2020;Gan et al, 2019;Willaert, 2009). ISSN 2166-0379 2020…”