Background When scaling up a monoclonal antibody (mAb) production process in stirred tank bioreactor, oxygen transfer is probably one of the most challenging parameters to consider. Approaches such as keeping constant specific power input or tip speed across the scales are widely described in the literature and are often based on the assumption that mammalian cells are sensitive to shear stress...

Two models of heparin coated, hollow fiber membrane oxygenators were tested in vitro to compare gas transfer and transoxygenator pressure drop using an established protocol. Oxygen and carbon dioxide transfer rates were measured at blood flows of 2.5 and 5.0 liters per minute with gas flow: blood flow ratios of 1:1 and 2:1 at both blood flows. All testing was performed under normothermic condit...

The productivity of enzyme fermentations depends critically on maintaining a high oxygen transfer rate to satisfy the optimal oxygen demand of the microorganism for product formation. Among the several factors that affect oxygen transfer rates in a fermentor are the air flow rate and agitation. The production of a-amylase by Bacillus amyloliquefaciens was performed in 600-mL and 5-litre ferment...

Modifying a gold electrode surface with hydroxy-alkyl-thiols significantly reduces the observed rate of electron transfer. This designed and controlled decrease in electron transfer rate readily allows reversible and irreversible electrode processes to be more clearly delineated. Separation of such voltammetric responses can facilitate the direct study of redox catalytic processes, which would,...

BACKGROUND The oxygen transfer rate (OTR) and dissolved oxygen tension (DOT) play an important role in determining alginate production and its composition; however, no systematic study has been reported about the independent influence of the OTR and DOT. In this paper, we report a study about alginate production and the evolution of the molecular mass of the polymer produced by a wild-type A. v...

The effect of the growth rate and oxygen transfer rate on Debaryomyces hansenii physiology was studied using xylose-limited and oxygen-limited chemostat cultures respectively, and complemented with enzymatic assays. Under xylose-limited chemostat (oxygen-excess) neither ethanol nor xylitol was produced over the entire range of dilution rate (D). The maximal volumetric biomass productivity was 2...

Pseudomonas aeruginosa PAO1 was recently found to exhibit two remarkable physiological responses to oxidative stress: (1) a strong reduction in the efficiency of oxygen transfer from the gas phase into the liquid phase, thus causing oxygen limitation in the culture and (2) formation of a clear polysaccharide capsule on the cell surface. In this work, it has been shown that the iron concentratio...