Production of cytidine 5′-monophospho-N-acetyl-β-D-neuraminic acid (CMP-sialic acid) using enzymes or whole cells entrapped in calcium pectate-silica-gel beads

The present study focuses on the application of immobilization technology to enzymic sugar syntheses. The paper describes an improved silica-alginate matrix established for entrapment and encapsulation. The replacement of alginate with pectate provided enhanced chemical resistance of the matrix, which allows the use of 1% (w/v) polyphosphate in reaction mixtures. Polylysine, a reagent for silica condensation, was replaced by a much cheaper alternative, namely polyethyleneimine. The proposed design was applied in the production of cytidine 5'-monophospho-N-acetyl-beta-D-neuraminic acid (CMP-sialic acid) by immobilized recombinant enzymes or Escherichia coli cells containing overexpressed enzymes. A comparison between these two strategies was made. On the basis of the results we conceptualized a system to synthesize sialyloligosaccharides by using a biocatalyst entrapped in calcium pectate-silica gel beads.