In situ magnetic separation for extracellular protein production

Abstract

A new approach for in situ product removal from bioreactors is presented in which high-gradient magnetic separation is used. This separation process was used for the adsorptive removal of proteases secreted by Bacillus licheniformis. Small, non-porous bacitracin linked magnetic adsorbents were employed directly in the broth during the fermentation, followed by in situ magnetic separation. Proof of the concept was first demonstrated in shake flask culture, then scaled up and applied during a fed batch cultivation in a 3.7 L bioreactor. It could be demonstrated that growth of B. licheniformis was not influenced by the in situ product removal step. Protease production also remained the same after the separation step. Furthermore, degradation of the protease, which followed first order kinetics, was reduced by using the method. Using a theoretical modeling approach, we could show that protease yield in total was enhanced by using in situ magnetic separation. The process described here is a promising technique to improve overall yield in bio production processes which are often limited due to weak downstream operations. Potential limitations encountered during a bioprocess can be overcome such as product inhibition or degradation. We also discuss the key points where research is needed to implement in situ magnetic separation in industrial production.

Harvesting fresh water and marine algae by magnetic separation: Screening of separation parameters and high gradient magnetic filtration

“…Precipitation of magnetic iron oxides such as magnetite (Fe 3 O 4 ) was conducted at room temperature under basic conditions as described in literature (Käppler et al, 2009). This material is furthermore referred to as ''precipitated magnetite''.…”

“…Especially high gradient magnetic filtration (HGMF) can be efficiently operated in combination with permanent magnets (Franzreb, 2003). Magnetic separation has already been successfully established for the in situ removal of extracellular proteins from biosuspension (Franzreb et al, 2006;Käppler et al, 2009) and immobilization of enzymes and whole cells (Li et al, 2009;Safarik and Safarikova, 2009). However, magnetic particles need to fulfill requirements to maintain a high overall efficiency of the process: reusability, chemical stability, adsorptive capacity and the ability of being produced as a low-cost bulk product (Franzreb et al, 2006).…”

High-gradient magnetic separation for technical scale protein recovery using low cost magnetic nanoparticles

“…Their use for biotechnological purposes began in the early 1970s [13] and is still common today though generally in the form of batch separators [14,15], although in a recently published work Lindner and Nirschl report on the combination of HGMS and centrifugation to generate a continuous process [16]. The number of published biotechnological large-scale HGMS applications is still low [17][18][19][20][21]. Specifically Franzreb and different collaborators have been working intensively in the field, reporting on HGMS methodology and parameters [6] as well as concrete application examples with micron beads as carriers e.g.…”

Dynamics of magnetic particles in cylindrical Halbach array: implications for magnetic cell separation and drug targeting

“…There is nowadays focusing attention on applications of magnetic fields acting on magnetic micro-as well as nanoparticles carrying target cells or molecules in the research field of magnetic cell and molecule separation [1,2], drug targeting [3][4][5][6], tumor embolization [7] and gene therapy [8,9].…”