SummaryOxygen solution rates were measured in 4, 30, and 100 liter culture vessels, and the oxygen demand of growing BHK 21 cells estimated. This data was used to calculate the minimal sparged air rates necessary to satisfy oxygen demand throughout the cell growth cycle, and in this way adequate oxygen was supplied without the damaging effects of excessive sparging. Comparable results were obtained when oxygen was supplied by this method and when pOz was controlled a t 80 mmHg, but both cell growth rate and maximum cell density were reduced when p02 was controlled at other values.
The growth of Semliki Forest Virus in st,irred culture vessels at volumes of 4 and 30 1. is described. Virus can be produced on a large scale in deep culture using industrial type vessels. Control of pII within close limits is important for maximum production of itifective virus. With the parent strain of SFV, virus yields were found to be influenced by an interference phenomenon which was apparently not due to interferon. Growth of a cloned strain of SFV obtained by serial selection of large plaques was not affected by this phenomenon. The cloned strain, when inoculated at a cell/virus input ratio of 1 :
A medium is described which will support the submerged culture of BHK-21 cells to 6.5 X 106 to 7 X 106 cells/mi in volumes up to 30 liters. Shaken-flask cultures were used to determine nutrient deficiencies in depleted medium. The final medium became limited by glutamine at 6.5 X 106 to 7 X 106 cells/ml, but increasing the glutamine concentration failed to improve cell yields. The value of the polyol Pluronic F68 as a protective substance is illustrated.
A tangential flow filtration unit is described through which cell suspension is continuously recycled. A pressure drop is incurred across the filter which forces liquid through the filter sheet, and cells in the remaining suspension are thus concentrated. The unit described has been used to concentrate 4 1 of cell suspension containing at least 2 × 106 cells/ml 12‐to 23‐fold in 2 to 4 h, with 94% viable cell recovery and little loss of viability. The filter is amenable to scale‐up and a pilot scale version is under test in this laboratory.
A medium is described which will support the submerged culture of BHK-21 cells to 6.5 × 10
6
to 7 × 10
6
cells/ml in volumes up to 30 liters. Shaken-flask cultures were used to determine nutrient deficiencies in depleted medium. The final medium became limited by glutamine at 6.5 × 10
6
to 7 × 10
6
cells/ml, but increasing the glutamine concentration failed to improve cell yields. The value of the polyol Pluronic F68 as a protective substance is illustrated.
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