title: Effect of metal ion concentration on a biological reactor.
abstract: Saccharomyces cerevisiae (yeast) cells were employed as a source of alcohol dehydrogenase in the NAD(+)-to-NADH reaction. The cells were immobilized in calcium alginate monofilament fibers and used in a biological reactor. The alginate could not be heat sterilized since temperatures above 80 degrees C caused the polymer chains to degrade. The same proved true for the high pH necessary for the reaction, but the alginate strength was increased by Ba(2+) solution treatment. X-ray probe analysis showed that about 30% of the Ca(2+) sites exchanged with the Ba(2+) ions. The Ba(2+) ions (as well as the Ca(2+) ions) permeabilized the cells and increased the reaction rate. Long term trials showed that Ba(2+) ions were slowly elutriated from the fiber biocatalyst, causing a drop in reaction rate. The trend certainly was reversible as far as the fiber was concerned. It is assumed that the permeabilization of the cells by the Ba(2+) ions was a reversible process.
authors.affiliation: Department of Chemical Engineering, Queen's University of Belfast, Belfast, Northern Ireland BT9 5AH.
authors.forename: P G
authors.initials: PG
authors.lastname: Ibbotson
authors.forename: P L
authors.initials: PL
authors.lastname: Spedding
authors.forename: M S
authors.initials: MS
authors.lastname: Otterburn