Step change in the efficiency of centrifugation through cell engineering: co-expression of Staphylococcal nuclease to reduce the viscosity of the bioprocess feedstock

Cell engineering to enable step change improvements in bioprocessing can be directed at targets other than increasing product titer. The physical properties of the process suspension such as viscosity, for example, have a major impact on various downstream processing unit operations. The release of...

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Bibliographic Details
Published in:Biotechnology and bioengineering 2009-09, Vol.104 (1), p.134-142
Main Authors: Balasundaram, B, Nesbeth, D, Ward, J.M, Keshavarz-Moore, E, Bracewell, D.G
Format: Article
Language:English
Subjects:
Biological and medical sciences
Biotechnology
cell disruption
cell engineering
Cells
Centrifugation - methods
clarification
Deoxyribonucleic acid
DNA
E coli
Escherichia coli
Escherichia coli - chemistry
Escherichia coli - genetics
Escherichia coli Proteins - isolation & purification
Fundamental and applied biological sciences. Psychology
Micrococcal Nuclease - genetics
Micrococcal Nuclease - metabolism
nuclease
Recombinant Proteins - genetics
Recombinant Proteins - metabolism
Staphylococcus aureus
Staphylococcus infections
Viscosity
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Summary:Cell engineering to enable step change improvements in bioprocessing can be directed at targets other than increasing product titer. The physical properties of the process suspension such as viscosity, for example, have a major impact on various downstream processing unit operations. The release of chromosomal DNA during homogenization of Escherichia coli and its influence on viscosity is well-recognized. In this current article we demonstrate co-expression of Staphylococcus aureus nuclease in E. coli to reduce viscosity through auto-hydrolysis of nucleic acids. Viscosity reduction of up to 75% was achieved while the particle size distribution of cell debris was maintained approximately constant (d₅₀ = 0.5-0.6 μm). Critically, resultant step change improvements to the clarification performance under disc-stack centrifugation conditions are shown. The cell-engineered nuclease matched or exceeded the viscosity reduction performance seen with the addition of exogenous nuclease removing the expense and validation issues associated with such additions to a bioprocess. The resultant material dramatically altered performance in scale-down mimics of continuous disc-stack centrifugation. Laboratory scale data indicated that a fourfold reduction in the settling area of a disc-stack centrifuge can be expected due to a less viscous process stream achieved through nuclease co-expression with a recombinant protein. Biotechnol. Bioeng. 2009; 104: 134-142
ISSN:0006-3592
1097-0290
DOI:10.1002/bit.22369