Effect of flow pattern on cellulase deactivation in stirred tank bioreactors

Ghadge, Rajaram; Patwardhan, Ashwin W.; Sawant, S.B.; Joshi, Jyeshtharaj B.

doi:10.1016/j.ces.2004.09.069

Cited by 49 publications

(25 citation statements)

References 41 publications

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“…However, fluid flow in processing is often turbulent and it is sometimes claimed that turbulence can result in additional forces on molecules above those caused by the mean flow. For example, Joshi et al(2001) and Ghadge et al(2005) claimed that deactivation of some enzymes in processing equipment could be correlated with the "volume average turbulent normal stress". However, even these authors recognized that enzyme molecules are much smaller than the Kolmogorov length scale of turbulence, even at high local energy dissipation rates.…”

Section: General Aspectsmentioning

confidence: 99%

“…At this scale, the energy carried by turbulent eddies is being dispersed as heat; indeed smaller eddies have little kinetic energy and are unlikely to cause shear damage to a protein. According to Ghadge et al(2005), the maximum energy dissipation rate was about 150 kW m -3 at 1 kW m -3 power input per unit volume to a stirred tank. This gives a Kolmogorov microscale of ca.…”

Section: General Aspectsmentioning

confidence: 99%

“…Such shear effects are important in processing of proteins in solution e.g. in the manufacture of enzymes (Ghadge et al 2005) and in the fermentation, purification, formulation, fill and finish operations for protein drug products (Rathore and Rajan 2008).…”

Section: Introductionmentioning

confidence: 99%

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Effects of shear on proteins in solution

2010

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The effects of "shear" on proteins in solution are described and discussed. Research on this topic covers many decades, beginning with investigations of possible denaturation of enzymes during processing, whilst more recent concerns are how the quality of therapeutic proteins might be affected by shear or shear related effects.The paradigm that emerges from most studies is that shear in the fluid mechanical sense is unlikely by itself to damage most proteins and that interfacial phenomena are critically important. In particular, moving gas-liquid interfaces can be very deleterious. Aggregation of therapeutic proteins on nanoparticles shed from solid surfaces is a recent concern because of potential consequences on patient safety. It is clear that labeling such damage as "shear" is a mistake as this inhibits clear investigations of, and thinking about, the true causes of damage to proteins in solution during processing.

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Section: General Aspectsmentioning

confidence: 99%

Section: General Aspectsmentioning

confidence: 99%

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Effects of shear on proteins in solution

2010

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“…Changes in enzyme activity are also observed in conditions when the morphological changes in cells are not yet visible [52,71,78,[80][81][82][83][84], which means that the deformation of cells as well as the damages and destruction of the cell membrane are a manifestation of the extreme stress, while the inner structures of the cell react to the hydrodynamic stress at much lower values of the turbulence intensity. If the enzyme activity of cells changes, then the amount and content of the metabolism product also must change.…”

Section: Figmentioning

confidence: 99%

“…Although the negative effects of turbohypobiosis are mentioned in many cases -decreased growing velocity of biomass [52,71,78,79,83] and/or decreased synthesis of the end product [78,89], for example, Ghadge et al [82] and Kaya et al [84] established a decrease in the cellulase activity with increasing mixing intensity or time. Sometimes the obtained results are quite different -Marten et al [80] described the maximum cellulase activity in more intensive mixing conditions.…”

Section: Figmentioning

confidence: 99%

Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

2007

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Abstract:The present review describes the influence of different types of mixing systems under excess turbulence conditions on microorganisms. Turbohypobiosis phenomena were described by applying a method for measurement of the kinetic energy of flow fluctuations based on the piezoeffect. It can be assumed that the shear stress effect (the state of turbohypobiosis) plays a role mainly when alternative mechanisms in cells cannot ensure a normal physiological state under stress conditions. Practically any system (inner construction of a bioreactor, culture and cultivation conditions, including mixing) requires its own optimisation to achieve the final goal, namely, the maximum product and/or biomass yields from substrate (Y P/S or/and Y X/S ), respectively. Data on the biotechnological performance of cultivation as well as power input, kinetic energy (e) of flow fluctuations, air consumption rate, rotational speed, tip speed, etc. do not correlate directly if the mixing systems (impellers-baffles) are dissimilar. Even the widely used specific power consumption cannot be relied upon for scaling up the cultivation performance using dissimilar mixing systems. A biochemical explanation for substrate and product transport via cell walls, carbon pathways, energy generation and utilisation, etc. furnishes insight into cellular interactions with turbulence of different origin for different types of microorganisms (single cells, mycelia forming cells, etc.

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Effect of flow pattern on cellulase deactivation in stirred tank bioreactors

Cited by 49 publications

References 41 publications

Effects of shear on proteins in solution

Effects of shear on proteins in solution

Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

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