Cross-linked cell aggregates of Trigonopsis variabilis: D-amino acid oxidase catalyst for oxidation of cephalosporin C.

Trigonopsis variabilis CBS 4095 was treated with alkali (pH 11, 30 min), heated (65 degrees C, 60 s) and immobilized. Glutaraldehyde, polyethyleneimine and a cross-linking reagent formed by reaction of polyethyleneimine with glutaraldehyde were used for stabilization of D-amino acid oxidase in the cells, as well as for aggregation and binding of the cells. A specific activity of 82-98 U of D-amino acid oxidase per g dry mass was produced with a yield of about 20%. The half-life time of 142 repeated conversion cycles corresponds to a productivity of 130 kg cephalosporin C oxidized per kg catalyst dry mass.