Bioprocess intensification in flow‐through monolithic microbioreactors with immobilized bacteria

Abstract

Microporous polymers (with porosity up to 90%) with a well-prescribed internal microstructure were prepared in monolithic form to construct a flow-through microbioreactor in which phenol-degrading bacteria, Pseudomonas syringae, was immobilized. Initially, bacteria was forced seeded within the pores and subsequently allowed to proliferate followed by acclimatization and phenol degradation at various initial substrate concentrations and flow rates. Two types of microporous polymer were used as the monolithic support. These polymers differ with respect to their pore and interconnect sizes, macroscopic surface area for bacterial support, and phase volume. Polymer with a nominal pore size of 100 microm with phase volume of 90% (with highly open pore structure) yielded reduced bacterial proliferation, while the polymer with nominal pore size of 25 microm with phase volume of 85% (with small interconnect size and large pore area for bacterial adhesion) yielded monolayer bacterial proliferation. Bacteria within the 25 microm polymer support remained monolayered, without any apparent production of extracellular matrix during the 30-day continuous experimental period. The microbioreactor performance was characterized in terms of volumetric utilization rate and compared with the published data, including the case where the same bacteria was immobilized on the surface of microporous polymer beads and used in a packed bed during continuous degradation of phenol. It is shown that at similar initial substrate concentration, the volumetric utilization in the microreactor is at least 20-fold more efficient than the packed bed, depending on the flow rate of the substrate solution. The concentration of the bacteria within the pores of the microreactor decreases from 2.25 cells per microm2 on the top surface to about 0.4 cells per microm2 within 3 mm reactor depth. If the bacteria-depleted part of the microreactor is disregarded, the volumetric utilization increases by a factor of 30-fold compared with the packed bed. This efficiency increase is attributed to the reduction of diffusion path for the substrate and nutrients and enhanced availability of the bacteria for bioconversion in the absence of biofilm formation as well as the presence of flow over the surface of the monolayer bacteria.

Synthetic organs for transplant and bio-mimic reactors for process intensification using nano-structured micro-porous materials

“…Recently, we have shown that bioprocesses could be intensified (Bioprocess Intensification) through the immobilization of bacteria within the micro-pores (within certain size range) of nano-structured micro-porous polymers which alter the metabolic activity of the bacteria [7]. This phenomenon is similar to that we observed for mammalian cells whereby the cell proliferation, protein production rate and differentiation are dependent on the size of the micro-environment that they grow [8][9][10][11].…”

“…As shown previously [1,[7][8][9][10][11]] the pore and interconnecting hole sized as well as the pore volume are important in the growth, viability and differentiation of cells in vitro. While the architecture of the support provides a 3D-culture and cell-cell communication, biochemical compatibility or even biochemical activation of the cells can be achieved by the chemical composition of the nanostructured micro-porous support material.…”

Engineered ecosystem development for Agro-Process Intensification

“…These materials act as micro-bioreactors for the efficient delivery of water and nutrients to the plant roots and preserve the activity of bacteria by creating a synthetic rhizosphere, essentially modifying the ecosystem. However, in order to ensure that the plant roots selectively seek and associate with SRS, several restrictions are placed on the type of material used as SRS; they include high water adsorption rate and capacity, elasticity, pore size, nano-porosity of the pore walls, ability to act as an efficient support for bacteria so as to utilise the 'confinement phenomenon' to achieve BioProcess Intensification [9,10]. AgroProcess Intensification through the application of process intensification and miniaturization principles is only possible if the root growth selectively targets the symbiotic media and root hairs and primary roots extensively form a network through it.…”

Intensified demulsification and separation of thermal oxide reprocessing interfacial crud (THORP-IFC) simulants

“…For example, this phenomenon has already been applied to the demulsifi cation of highly stable water-incrude oil emulsions [12] , using particles of hydrophilic microporous polymers known as PolyHIPE Polymers (PHPs) under static conditions [7] , or under fl ow conditions in the absence or presence of an electric fi eld [5,12] . The other applications of the confi nement phenomenon include tissue engineering [28,29] and bioprocess intensifi cation [30] .…”