BIOREACTOR SYSTEM ERT 314 DR HUZAIRY HASSAN SCHOOL
BIOREACTOR SYSTEM ERT 314 DR HUZAIRY HASSAN SCHOOL OF BIOPROCESS ENGINEERING, UNIMAP SEMESTER 2 2017/2018
CHAPTER 4 BIOREACTOR CONSIDERATIONS FOR SUSPENSION, IMMOBILIZED, ANIMAL AND PLANT CELL CULTURES Ø Differences Ø Ø between batch and continuous system based on productivity Modifications for batch and continuous bioreactor Simple bioreactor design for immobilized cell systems, animal and plant cell cultures Ø Solid state fermentation process
Immobilized Cell Systems Introduction As biocatalysts and as common as enzyme immobilization Advantages over suspension cultures: High cell concentrations Provides favorable micro-environmental conditions Provides cell reuse (eliminate costs cell recovery & recycle) Eliminate cell washout problems at high D Improves genetic instability Combination of high cell conc. & high flow rates high V productivity Protection against shear damage is important
Immobilized Cell Systems Introduction Disadvantages: Product should be excreted by the cells Living cells, growth and gas evolution Diffusional limitation Mechanical disruption Difficult to control microenvironmental conditions Heterogeneity
Immobilized Cell Systems Introduction Cell immobilization vs. Enzyme immobilization - Maintenance of living cell in such system is more complex than maintaining enzyme activity. - Immobilized cells can perform multistep, co-factor requiring, biosynthetic reactions that are not practical using purified enzyme preparations.
Immobilized Cell Systems Active Immobilization of Cells § Is entrapment or binding of cells by physical or chemical forces. § Physical entrapment within porous matrices most widely used. § Porous polymers (agar, alginate, κ-carrageenan, polyacrylamide, chitosan, gelatin, collagen), porous metal screens, polyurethane, silica gel, polystyrene, cellulose triacetate.
Immobilized Cell Systems Active Immobilization of Cells § Polymer beads should be porous enough to allow the transport of substrates and products in and out of the bead. § Formed in the presence of cells and can be prepared by one of the following methods: 1) Gelation of polymers 2) Precipitation of polymers 3) Ion-exchange gelation 4) Polycondensation 5) Polymerization
Immobilized Cell Systems Active Immobilization of Cells q Other methods in cell immobilizations? ? ? 1) Encapsulation – Microcapsules / macroscopic membranes 2) Adsorption – covalent binding 3) Direct cross-linking of cells
Immobilized Cell Systems Active Immobilization of Cells
Immobilized Cell Systems Active Immobilization of Cells
Immobilized Cell Systems Passive Immobilization: Biological Films ü Biological films (Biofilms) are the multilayer growth of cells on solid support surfaces. ü The support material can be inert or biologically active. ü Biofilm formation is common in natural and industrial fermentation systems (biological waste-water treatment & mold fermentation) ü Interactions among cells – binding forces
Immobilized Cell Systems Passive Immobilization: Biological Films ü Mixed culture microbial films – presence of some polymer-producing organisms facilitate biofilm formation & enhances biofilm stability. ü Nutrients diffuse into the biofilm, and products diffuse out into liquid medium. ü Biofilm thickness varies – affect cell physiology Thin biofilm – have low rates of conversion due to low biomass conc. Thick biofilm – may experience diffusionally limited growth ü Most sparingly soluble nutrient, i. e. , dissolved oxygen – rate limiting nutrient. Huzairy Hassan, Bo Jin, Sheng Dai, and Cornelius Ngau, 2016, Formation of industrial mixed culture biofilm in chlorophenol cultivated medium of microbial fuel cell, http: //dx. doi. org/10. 1063/1. 4968084
Immobilized Cell Systems Passive Immobilization: Biological Films
Immobilized Cell Systems Passive Immobilization: Biological Films
Immobilized Cell Systems Da >> 1 the rate of bioconversion is diffusion limited. Da << 1 the rate is limited by the rate of bioconversion. Da ≈ 1 the diffusion and bioreaction rates are comparable. It is desirable to keep Da < 1 to eliminate diffusion limitations when the productivity of a cell population does not improve upon immobilization due to cell-cell contact and nutrient gradients.
Immobilized Cell Systems Diffusional Limitations in Immobilized Cell Systems
Immobilized Cell Systems Diffusional Limitations in Immobilized Cell Systems
Immobilized Cell Systems Diffusional Limitations in Immobilized Cell Systems - ϕ should be low (ϕ <1) to eliminate dl. - As biofilm grows, ϕ will gradually increase - If shear forces cause portion of biofilm to detach, then ϕ decreases abruptly
Immobilized Cell Systems Diffusional Limitations in Immobilized Cell Systems
Immobilized Cell Systems Diffusional Limitations in Immobilized Cell Systems
Immobilized Cell Systems Diffusional Limitations in Immobilized Cell Systems
Immobilized Cell Systems Bioreactor Considerations in Immobilized Cell Systems Since the support matrices used are often mechanically fragile, bioreactors with low hydrodynamic shear, such as packed-column, fluidized-bed, or airlift reactors, are preferred. Operated in perfusion mode by passing nutrient solution through a column of immobilized cells. Can be operated in batch or continuous mode.
Immobilized Cell Systems Bioreactor Considerations in Immobilized Cell Systems
Immobilized Cell Systems Bioreactor Considerations in Immobilized Cell Systems
Immobilized Cell Systems Bioreactor Considerations in Immobilized Cell Systems
Immobilized Cell Systems Bioreactor Considerations in Immobilized Cell Systems http: //www. informit. com/articles/article. aspx? p=2475565&seq. Num=4
Example 9. 4
Solid-state Fermentation Arora, S. , Rani, R. , Ghosh, S. , Bioreactors in solid state fermentation technology: Design, applications and engineering aspects, J. Biotechnol. 269 (2018) 16 -34.
Solid-state Fermentation
Solid-state Fermentation Bioreactor classification: 1. 2. 3. 4. Tray bioreactor Packed bioreactor Air pressure pulsation bioreactor Intermittent or continuously mixed SSF bioreactor
Solid-state Fermentation Tray Bioreactor
Solid-state Fermentation Tray Bioreactor
Solid-state Fermentation Packed Bioreactor
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