Acetic Acid Production by Immobilized Acetobacter aceti Cells Entrapped in a k-Carrageenan Gel

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Immobilized growing acetic acid bacterial cells were prepared with k-carrageenan.Gel beads were incubated with continuous feeding of a complete medoum into a fluidized bed reactor with good agitation, and after 2 days the cell number in the gel reached 100 times the initial number. Then the gel beads were fed a production medium and reached the maximum production activity of acetic acid of 40.1 mg(ml gel・h) with pure oxygen gas. Oxygen was the limiting factor for increasing the cell number and raising production activity.Feeding a production medium at a higher dilution rate than the wash out point in free cell culture, a steady production was carried out at a production rate of about 4 mg/(ml liquid・h) for 120 days. Residence time of 2 to 4.5 h did not have effects on the production rate of acetic acid. By optical and electron microscopic observation, the bacteria formed giant colonies and constituted a density layer near the surface of the gel. The cells were gradually released from the gel into the broth through the craters on its surface. The bacteria seemed to keep a steady high production rate by collaboration of the cells in gel and the released cells.It was concluded that the immobilized growing cell system was extremely advantageous for aerobic fermentation as well as anaerobic fermentation.
公益社団法人日本生物工学会の論文
1984-04-25