Production of ampicillin through Escherichia coli NCIM 2563 immobilized and cross-linked in alginate beads.

6-Amino penicillanic acid (6-APA) was condensed with D-alpha-phenyl glycine chloride in presence of E. coli NCIM 2563 to form ampicillin. At pH 5, 30% of 6-APA was converted to ampicillin during 1 hr incubation. When E. coli cells were immobilized in calcium alginate beads, the activity remained unaffected even after six batches of bioconversion. Inclusion of glutaraldehyde as multifunctional cross-linking agent, improved the stability of the biocatalyst beads.