The effect of dissolved oxygen concentrations on the behavior of Serratia marcescens and on yields of asparaginase and prodigiosin produced in shaken cultures and in a 55-liter stainless-steel fermentor was studied. A range of oxygen transfer rates was obtained in 500-ml Erlenmeyer flasks by using internal, stainless-steel baffles and by varying the volume of medium per flask, and in the fermen...

Fish respire through gills, which have evolved to extract aqueous oxygen. Fish gills consist of filaments with well-ordered lamellar structures, which play a role in maximizing oxygen diffusion. It is interesting that when we anatomically observe the gills of various fish species, gill interlamellar distances (d) vary little among them, despite large variations in body mass (Mb). Noting that th...

background: in spite of the great progress in assisted reproductive techniques ( art) and although good quality embryos are transferred pregnancy rates have remained around 30%-35% due to low implantation rates. objective: the aim of this study was to assess and compare the effects of administrating indomethacin or hyoscine suppositories prior to embryo transfer on the pregnancy rate in art cyc...

SUMMARY Pseudomonas aeruginosa PAO1 was recently reported to exhibit an unusual property of dramatically reducing the efficiency of oxygen transfer from the gas phase into the liquid phase and thus causing oxygen limitation in the culture. In this work, we show that iron concentration in the culture plays a crucial role in evoking this phenomenon. The physiological responses of two P. aeruginos...

Oxygen transfer has been studied in the Pseudomonas ovalis fermentation that quantitatively converts glucose into gluconic acid. The rate of oxygen uptake by this system was correlated with aeration rates and agitator speeds over wide ranges of these variables, by the introduction of a liquid expansion term. The technique described provides a biological method for studying oxygen transfer in th...

In many industrial fermentation processes oxygen availability is the main limiting factor for product production. Typically the dissolved oxygen (DO) concentration decreases continuously at the beginning of the batch until it reaches a critical level where the oxygen transfer rate is very close to the vessel’s maximum transfer capacity. The process may be further driven close to this sensitive ...